diff --git a/android_webview/android_webview.gyp b/android_webview/android_webview.gyp
index 2efc46c..a01b499 100644
--- a/android_webview/android_webview.gyp
+++ b/android_webview/android_webview.gyp
@@ -190,6 +190,8 @@
         'browser/net/init_native_callback.h',
         'browser/net/input_stream_reader.cc',
         'browser/net/input_stream_reader.h',
+        'browser/parent_compositor_draw_constraints.cc',
+        'browser/parent_compositor_draw_constraints.h',
         'browser/parent_output_surface.cc',
         'browser/parent_output_surface.h',
         'browser/renderer_host/aw_render_view_host_ext.cc',
diff --git a/android_webview/android_webview_common.target.darwin-arm.mk b/android_webview/android_webview_common.target.darwin-arm.mk
index e19a13b..9f3b0ce 100644
--- a/android_webview/android_webview_common.target.darwin-arm.mk
+++ b/android_webview/android_webview_common.target.darwin-arm.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.darwin-arm64.mk b/android_webview/android_webview_common.target.darwin-arm64.mk
index 42b6eee..2360d099 100644
--- a/android_webview/android_webview_common.target.darwin-arm64.mk
+++ b/android_webview/android_webview_common.target.darwin-arm64.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.darwin-mips.mk b/android_webview/android_webview_common.target.darwin-mips.mk
index 17fd1f8..4aee34b 100644
--- a/android_webview/android_webview_common.target.darwin-mips.mk
+++ b/android_webview/android_webview_common.target.darwin-mips.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.darwin-x86.mk b/android_webview/android_webview_common.target.darwin-x86.mk
index 73d4359..1b5cd85 100644
--- a/android_webview/android_webview_common.target.darwin-x86.mk
+++ b/android_webview/android_webview_common.target.darwin-x86.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.darwin-x86_64.mk b/android_webview/android_webview_common.target.darwin-x86_64.mk
index 320cfac..9dc3726 100644
--- a/android_webview/android_webview_common.target.darwin-x86_64.mk
+++ b/android_webview/android_webview_common.target.darwin-x86_64.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.linux-arm.mk b/android_webview/android_webview_common.target.linux-arm.mk
index e19a13b..9f3b0ce 100644
--- a/android_webview/android_webview_common.target.linux-arm.mk
+++ b/android_webview/android_webview_common.target.linux-arm.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.linux-arm64.mk b/android_webview/android_webview_common.target.linux-arm64.mk
index 42b6eee..2360d099 100644
--- a/android_webview/android_webview_common.target.linux-arm64.mk
+++ b/android_webview/android_webview_common.target.linux-arm64.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.linux-mips.mk b/android_webview/android_webview_common.target.linux-mips.mk
index 17fd1f8..4aee34b 100644
--- a/android_webview/android_webview_common.target.linux-mips.mk
+++ b/android_webview/android_webview_common.target.linux-mips.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.linux-x86.mk b/android_webview/android_webview_common.target.linux-x86.mk
index 73d4359..1b5cd85 100644
--- a/android_webview/android_webview_common.target.linux-x86.mk
+++ b/android_webview/android_webview_common.target.linux-x86.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/android_webview_common.target.linux-x86_64.mk b/android_webview/android_webview_common.target.linux-x86_64.mk
index 320cfac..9dc3726 100644
--- a/android_webview/android_webview_common.target.linux-x86_64.mk
+++ b/android_webview/android_webview_common.target.linux-x86_64.mk
@@ -62,6 +62,7 @@
 	android_webview/browser/net/aw_url_request_job_factory.cc \
 	android_webview/browser/net_disk_cache_remover.cc \
 	android_webview/browser/net/input_stream_reader.cc \
+	android_webview/browser/parent_compositor_draw_constraints.cc \
 	android_webview/browser/parent_output_surface.cc \
 	android_webview/browser/renderer_host/aw_render_view_host_ext.cc \
 	android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc \
diff --git a/android_webview/browser/browser_view_renderer.cc b/android_webview/browser/browser_view_renderer.cc
index c2875bc..bba3e4a 100644
--- a/android_webview/browser/browser_view_renderer.cc
+++ b/android_webview/browser/browser_view_renderer.cc
@@ -255,14 +255,29 @@
   draw_gl_input->width = width_;
   draw_gl_input->height = height_;
 
-  gfx::Transform transform;
+  parent_draw_constraints_ = shared_renderer_state_->ParentDrawConstraints();
   gfx::Size surface_size(width_, height_);
   gfx::Rect viewport(surface_size);
-  // TODO(boliu): Should really be |last_on_draw_global_visible_rect_|.
-  // See crbug.com/372073.
   gfx::Rect clip = viewport;
-  scoped_ptr<cc::CompositorFrame> frame = compositor_->DemandDrawHw(
-      surface_size, transform, viewport, clip);
+  gfx::Transform transform_for_tile_priority =
+      parent_draw_constraints_.transform;
+
+  // If the WebView is on a layer, WebView does not know what transform is
+  // applied onto the layer so global visible rect does not make sense here.
+  // In this case, just use the surface rect for tiling.
+  gfx::Rect viewport_rect_for_tile_priority;
+  if (parent_draw_constraints_.is_layer)
+    viewport_rect_for_tile_priority = parent_draw_constraints_.surface_rect;
+  else
+    viewport_rect_for_tile_priority = last_on_draw_global_visible_rect_;
+
+  scoped_ptr<cc::CompositorFrame> frame =
+      compositor_->DemandDrawHw(surface_size,
+                                gfx::Transform(),
+                                viewport,
+                                clip,
+                                viewport_rect_for_tile_priority,
+                                transform_for_tile_priority);
   if (!frame.get())
     return false;
 
@@ -275,6 +290,14 @@
   return client_->RequestDrawGL(java_canvas, false);
 }
 
+void BrowserViewRenderer::UpdateParentDrawConstraints() {
+  // Post an invalidate if the parent draw constraints are stale and there is
+  // no pending invalidate.
+  if (!parent_draw_constraints_.Equals(
+          shared_renderer_state_->ParentDrawConstraints()))
+    EnsureContinuousInvalidation(true);
+}
+
 void BrowserViewRenderer::ReturnUnusedResource(scoped_ptr<DrawGLInput> input) {
   if (!input.get())
     return;
diff --git a/android_webview/browser/browser_view_renderer.h b/android_webview/browser/browser_view_renderer.h
index e130334..bf660df 100644
--- a/android_webview/browser/browser_view_renderer.h
+++ b/android_webview/browser/browser_view_renderer.h
@@ -7,6 +7,7 @@
 
 #include "android_webview/browser/global_tile_manager.h"
 #include "android_webview/browser/global_tile_manager_client.h"
+#include "android_webview/browser/parent_compositor_draw_constraints.h"
 #include "android_webview/browser/shared_renderer_state.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/callback.h"
@@ -140,6 +141,8 @@
   virtual void SetNumTiles(size_t num_tiles,
                            bool effective_immediately) OVERRIDE;
 
+  void UpdateParentDrawConstraints();
+
  private:
   void SetTotalRootLayerScrollOffset(gfx::Vector2dF new_value_dip);
   // Checks the continuous invalidate and block invalidate state, and schedule
@@ -199,6 +202,10 @@
   gfx::Vector2d last_on_draw_scroll_offset_;
   gfx::Rect last_on_draw_global_visible_rect_;
 
+  // The draw constraints from the parent compositor. These are only used for
+  // tiling priority.
+  ParentCompositorDrawConstraints parent_draw_constraints_;
+
   // When true, we should continuously invalidate and keep drawing, for example
   // to drive animation. This value is set by the compositor and should always
   // reflect the expectation of the compositor and not be reused for other
diff --git a/android_webview/browser/browser_view_renderer_client.h b/android_webview/browser/browser_view_renderer_client.h
index 41fbf5a..2fba4d2 100644
--- a/android_webview/browser/browser_view_renderer_client.h
+++ b/android_webview/browser/browser_view_renderer_client.h
@@ -28,6 +28,9 @@
   // Called to trigger view invalidations.
   virtual void PostInvalidate() = 0;
 
+  // Called to update the parent draw constraints in browser view renderer.
+  virtual void UpdateParentDrawConstraints() = 0;
+
   // Called to get view's absolute location on the screen.
   virtual gfx::Point GetLocationOnScreen() = 0;
 
diff --git a/android_webview/browser/hardware_renderer.cc b/android_webview/browser/hardware_renderer.cc
index df7e361..e0dab89 100644
--- a/android_webview/browser/hardware_renderer.cc
+++ b/android_webview/browser/hardware_renderer.cc
@@ -191,6 +191,21 @@
   if (last_egl_context_ != current_context)
     DLOG(WARNING) << "EGLContextChanged";
 
+  gfx::Transform transform(gfx::Transform::kSkipInitialization);
+  transform.matrix().setColMajorf(draw_info->transform);
+  transform.Translate(scroll_offset_.x(), scroll_offset_.y());
+
+  // Need to post the new transform matrix back to child compositor
+  // because there is no onDraw during a Render Thread animation, and child
+  // compositor might not have the tiles rasterized as the animation goes on.
+  ParentCompositorDrawConstraints draw_constraints(
+      draw_info->is_layer, transform, gfx::Rect(viewport_));
+  if (!draw_constraints_.Equals(draw_constraints)) {
+    draw_constraints_ = draw_constraints;
+    shared_renderer_state_->PostExternalDrawConstraintsToChildCompositor(
+        draw_constraints);
+  }
+
   viewport_.SetSize(draw_info->width, draw_info->height);
   layer_tree_host_->SetViewportSize(viewport_);
   clip_.SetRect(draw_info->clip_left,
@@ -199,9 +214,6 @@
                 draw_info->clip_bottom - draw_info->clip_top);
   stencil_enabled_ = stencil_enabled;
 
-  gfx::Transform transform(gfx::Transform::kSkipInitialization);
-  transform.matrix().setColMajorf(draw_info->transform);
-  transform.Translate(scroll_offset_.x(), scroll_offset_.y());
   delegated_layer_->SetTransform(transform);
 
   gl_surface_->SetBackingFrameBufferObject(framebuffer_binding_ext);
diff --git a/android_webview/browser/hardware_renderer.h b/android_webview/browser/hardware_renderer.h
index f69d587..f87890b 100644
--- a/android_webview/browser/hardware_renderer.h
+++ b/android_webview/browser/hardware_renderer.h
@@ -5,6 +5,7 @@
 #ifndef ANDROID_WEBVIEW_BROWSER_HARDWARE_RENDERER_H_
 #define ANDROID_WEBVIEW_BROWSER_HARDWARE_RENDERER_H_
 
+#include "android_webview/browser/parent_compositor_draw_constraints.h"
 #include "android_webview/browser/shared_renderer_state.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/layers/delegated_frame_resource_collection.h"
@@ -89,6 +90,8 @@
   // This is owned indirectly by |layer_tree_host_|.
   ParentOutputSurface* output_surface_;
 
+  ParentCompositorDrawConstraints draw_constraints_;
+
   DISALLOW_COPY_AND_ASSIGN(HardwareRenderer);
 };
 
diff --git a/android_webview/browser/parent_compositor_draw_constraints.cc b/android_webview/browser/parent_compositor_draw_constraints.cc
new file mode 100644
index 0000000..e507d43
--- /dev/null
+++ b/android_webview/browser/parent_compositor_draw_constraints.cc
@@ -0,0 +1,29 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "android_webview/browser/parent_compositor_draw_constraints.h"
+
+namespace android_webview {
+
+ParentCompositorDrawConstraints::ParentCompositorDrawConstraints()
+    : is_layer(false) {
+}
+
+ParentCompositorDrawConstraints::ParentCompositorDrawConstraints(
+    bool is_layer,
+    const gfx::Transform& transform,
+    const gfx::Rect& surface_rect)
+    : is_layer(is_layer), transform(transform), surface_rect(surface_rect) {
+}
+
+bool ParentCompositorDrawConstraints::Equals(
+    const ParentCompositorDrawConstraints& other) const {
+  if (is_layer != other.is_layer || transform != other.transform)
+    return false;
+
+  // Don't care about the surface size when neither is on a layer.
+  return !is_layer || surface_rect == other.surface_rect;
+}
+
+}  // namespace webview
diff --git a/android_webview/browser/parent_compositor_draw_constraints.h b/android_webview/browser/parent_compositor_draw_constraints.h
new file mode 100644
index 0000000..4355aa9
--- /dev/null
+++ b/android_webview/browser/parent_compositor_draw_constraints.h
@@ -0,0 +1,27 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ANDROID_WEBVIEW_BROWSER_PARENT_COMPOSITOR_DRAW_CONSTRAINTS_H_
+#define ANDROID_WEBVIEW_BROWSER_PARENT_COMPOSITOR_DRAW_CONSTRAINTS_H_
+
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/transform.h"
+
+namespace android_webview {
+
+struct ParentCompositorDrawConstraints {
+  bool is_layer;
+  gfx::Transform transform;
+  gfx::Rect surface_rect;
+
+  ParentCompositorDrawConstraints();
+  ParentCompositorDrawConstraints(bool is_layer,
+                                  const gfx::Transform& transform,
+                                  const gfx::Rect& surface_rect);
+  bool Equals(const ParentCompositorDrawConstraints& other) const;
+};
+
+}  // namespace android_webview
+
+#endif  // ANDROID_WEBVIEW_BROWSER_PARENT_COMPOSITOR_DRAW_CONSTRAINTS_H_
diff --git a/android_webview/browser/parent_output_surface.cc b/android_webview/browser/parent_output_surface.cc
index 54b7f97..0680bc7 100644
--- a/android_webview/browser/parent_output_surface.cc
+++ b/android_webview/browser/parent_output_surface.cc
@@ -30,7 +30,8 @@
   const gfx::Transform identity;
   const gfx::Rect empty;
   const bool resourceless_software_draw = false;
-  SetExternalDrawConstraints(identity, empty, clip, resourceless_software_draw);
+  SetExternalDrawConstraints(
+      identity, empty, clip, clip, identity, resourceless_software_draw);
 }
 
 }  // namespace android_webview
diff --git a/android_webview/browser/shared_renderer_state.cc b/android_webview/browser/shared_renderer_state.cc
index 582908e..200e2ab 100644
--- a/android_webview/browser/shared_renderer_state.cc
+++ b/android_webview/browser/shared_renderer_state.cc
@@ -51,6 +51,11 @@
   }
 }
 
+void SharedRendererState::UpdateParentDrawConstraintsOnUIThread() {
+  DCHECK(ui_loop_->BelongsToCurrentThread());
+  client_on_ui_->UpdateParentDrawConstraints();
+}
+
 void SharedRendererState::SetDrawGLInput(scoped_ptr<DrawGLInput> input) {
   base::AutoLock lock(lock_);
   DCHECK(!draw_gl_input_.get());
@@ -62,6 +67,26 @@
   return draw_gl_input_.Pass();
 }
 
+void SharedRendererState::PostExternalDrawConstraintsToChildCompositor(
+    const ParentCompositorDrawConstraints& parent_draw_constraints) {
+  {
+    base::AutoLock lock(lock_);
+    parent_draw_constraints_ = parent_draw_constraints;
+  }
+
+  // No need to hold the lock_ during the post task.
+  ui_loop_->PostTask(
+      FROM_HERE,
+      base::Bind(&SharedRendererState::UpdateParentDrawConstraintsOnUIThread,
+                 ui_thread_weak_ptr_));
+}
+
+const ParentCompositorDrawConstraints
+SharedRendererState::ParentDrawConstraints() const {
+  base::AutoLock lock(lock_);
+  return parent_draw_constraints_;
+}
+
 void SharedRendererState::SetInsideHardwareRelease(bool inside) {
   base::AutoLock lock(lock_);
   inside_hardware_release_ = inside;
diff --git a/android_webview/browser/shared_renderer_state.h b/android_webview/browser/shared_renderer_state.h
index 01363f1..cf0c889 100644
--- a/android_webview/browser/shared_renderer_state.h
+++ b/android_webview/browser/shared_renderer_state.h
@@ -5,6 +5,7 @@
 #ifndef ANDROID_WEBVIEW_BROWSER_SHARED_RENDERER_STATE_H_
 #define ANDROID_WEBVIEW_BROWSER_SHARED_RENDERER_STATE_H_
 
+#include "android_webview/browser/parent_compositor_draw_constraints.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/synchronization/lock.h"
@@ -50,6 +51,10 @@
   scoped_ptr<DrawGLInput> PassDrawGLInput();
 
   bool IsInsideHardwareRelease() const;
+  void PostExternalDrawConstraintsToChildCompositor(
+      const ParentCompositorDrawConstraints& parent_draw_constraints);
+
+  const ParentCompositorDrawConstraints ParentDrawConstraints() const;
 
   void SetSharedContext(gpu::GLInProcessContext* context);
   gpu::GLInProcessContext* GetSharedContext() const;
@@ -62,6 +67,7 @@
   friend class InsideHardwareReleaseReset;
 
   void ClientRequestDrawGLOnUIThread();
+  void UpdateParentDrawConstraintsOnUIThread();
   void SetInsideHardwareRelease(bool inside);
 
   scoped_refptr<base::MessageLoopProxy> ui_loop_;
@@ -73,6 +79,7 @@
   mutable base::Lock lock_;
   scoped_ptr<DrawGLInput> draw_gl_input_;
   bool inside_hardware_release_;
+  ParentCompositorDrawConstraints parent_draw_constraints_;
   gpu::GLInProcessContext* share_context_;
   cc::ReturnedResourceArray returned_resources_;
 
diff --git a/android_webview/native/aw_contents.cc b/android_webview/native/aw_contents.cc
index cc5e6a3..04b6da1 100644
--- a/android_webview/native/aw_contents.cc
+++ b/android_webview/native/aw_contents.cc
@@ -746,6 +746,11 @@
     Java_AwContents_postInvalidateOnAnimation(env, obj.obj());
 }
 
+void AwContents::UpdateParentDrawConstraints() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  browser_view_renderer_.UpdateParentDrawConstraints();
+}
+
 void AwContents::OnNewPicture() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   JNIEnv* env = AttachCurrentThread();
diff --git a/android_webview/native/aw_contents.h b/android_webview/native/aw_contents.h
index ddfeaf3..1381007 100644
--- a/android_webview/native/aw_contents.h
+++ b/android_webview/native/aw_contents.h
@@ -192,6 +192,7 @@
   // BrowserViewRendererClient implementation.
   virtual bool RequestDrawGL(jobject canvas, bool wait_for_completion) OVERRIDE;
   virtual void PostInvalidate() OVERRIDE;
+  virtual void UpdateParentDrawConstraints() OVERRIDE;
   virtual void OnNewPicture() OVERRIDE;
   virtual gfx::Point GetLocationOnScreen() OVERRIDE;
   virtual void ScrollContainerViewTo(gfx::Vector2d new_value) OVERRIDE;
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 52b1658..8759219 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -398,7 +398,8 @@
   // resourceless software draw, so don't update them.
   if (!layer_tree_impl()->resourceless_software_draw()) {
     visible_rect_for_tile_priority_ = visible_content_rect();
-    viewport_size_for_tile_priority_ = layer_tree_impl()->DrawViewportSize();
+    viewport_rect_for_tile_priority_ =
+        layer_tree_impl()->ViewportRectForTilePriority();
     screen_space_transform_for_tile_priority_ = screen_space_transform();
   }
 
@@ -457,16 +458,22 @@
   if (!tiling_needs_update)
     return;
 
-  // Use visible_content_rect, unless it's empty. If it's empty, then
-  // try to inverse project the viewport into layer space and use that.
+  // If visible_rect_for_tile_priority_ is empty or
+  // viewport_rect_for_tile_priority_ is set to be different from the device
+  // viewport, try to inverse project the viewport into layer space and use
+  // that. Otherwise just use visible_rect_for_tile_priority_
   gfx::Rect visible_rect_in_content_space = visible_rect_for_tile_priority_;
-  if (visible_rect_in_content_space.IsEmpty()) {
-    gfx::Transform screen_to_layer(gfx::Transform::kSkipInitialization);
-    if (screen_space_transform_for_tile_priority_.GetInverse(
-            &screen_to_layer)) {
+
+  if (visible_rect_in_content_space.IsEmpty() ||
+      layer_tree_impl()->DeviceViewport() != viewport_rect_for_tile_priority_) {
+    gfx::Transform view_to_layer(gfx::Transform::kSkipInitialization);
+
+    if (screen_space_transform_for_tile_priority_.GetInverse(&view_to_layer)) {
+      // Transform from view space to content space.
       visible_rect_in_content_space =
           gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
-              screen_to_layer, gfx::Rect(viewport_size_for_tile_priority_)));
+              view_to_layer, viewport_rect_for_tile_priority_));
+
       visible_rect_in_content_space.Intersect(gfx::Rect(content_bounds()));
     }
   }
diff --git a/cc/layers/picture_layer_impl.h b/cc/layers/picture_layer_impl.h
index 6b1703e..ad30821 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -201,7 +201,7 @@
   // Save a copy of the visible rect and viewport size of the last frame that
   // has a valid viewport for prioritizing tiles.
   gfx::Rect visible_rect_for_tile_priority_;
-  gfx::Size viewport_size_for_tile_priority_;
+  gfx::Rect viewport_rect_for_tile_priority_;
   gfx::Transform screen_space_transform_for_tile_priority_;
 
   friend class PictureLayer;
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 83b775e..180ed78 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -9,6 +9,7 @@
 #include <set>
 #include <utility>
 
+#include "cc/base/math_util.h"
 #include "cc/layers/append_quads_data.h"
 #include "cc/layers/picture_layer.h"
 #include "cc/test/fake_content_layer_client.h"
@@ -300,6 +301,103 @@
     VerifyAllTilesExistAndHavePile(tilings->tiling_at(i), active_pile.get());
 }
 
+TEST_F(PictureLayerImplTest, ExternalViewportRectForPrioritizingTiles) {
+  base::TimeTicks time_ticks;
+  host_impl_.SetCurrentFrameTimeTicks(time_ticks);
+  gfx::Size tile_size(100, 100);
+  gfx::Size layer_bounds(400, 400);
+
+  scoped_refptr<FakePicturePileImpl> pending_pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+  scoped_refptr<FakePicturePileImpl> active_pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  SetupTrees(pending_pile, active_pile);
+
+  Region invalidation;
+  AddDefaultTilingsWithInvalidation(invalidation);
+  SetupDrawPropertiesAndUpdateTiles(active_layer_, 1.f, 1.f, 1.f, 1.f, false);
+
+  // Update tiles with viewport for tile priority as (0, 0, 100, 100) and the
+  // identify transform for tile priority.
+  bool resourceless_software_draw = false;
+  gfx::Rect viewport = gfx::Rect(layer_bounds),
+            viewport_rect_for_tile_priority = gfx::Rect(0, 0, 100, 100);
+  gfx::Transform transform, transform_for_tile_priority;
+
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport_rect_for_tile_priority,
+                                        transform_for_tile_priority,
+                                        resourceless_software_draw);
+  active_layer_->draw_properties().visible_content_rect = viewport;
+  active_layer_->draw_properties().screen_space_transform = transform;
+  active_layer_->UpdateTiles();
+
+  gfx::Rect viewport_rect_for_tile_priority_in_view_space =
+      viewport_rect_for_tile_priority;
+
+  // Verify the viewport rect for tile priority is used in picture layer impl.
+  EXPECT_EQ(active_layer_->viewport_rect_for_tile_priority(),
+            viewport_rect_for_tile_priority_in_view_space);
+
+  // Verify the viewport rect for tile priority is used in picture layer tiling.
+  PictureLayerTilingSet* tilings = active_layer_->tilings();
+  for (size_t i = 0; i < tilings->num_tilings(); i++) {
+    PictureLayerTiling* tiling = tilings->tiling_at(i);
+    EXPECT_EQ(
+        tiling->GetCurrentVisibleRectForTesting(),
+        gfx::ScaleToEnclosingRect(viewport_rect_for_tile_priority_in_view_space,
+                                  tiling->contents_scale()));
+  }
+
+  // Update tiles with viewport for tile priority as (200, 200, 100, 100) in
+  // screen space and the transform for tile priority is translated and
+  // rotated. The actual viewport for tile priority used by PictureLayerImpl
+  // should be (200, 200, 100, 100) applied with the said transform.
+  time_ticks += base::TimeDelta::FromMilliseconds(200);
+  host_impl_.SetCurrentFrameTimeTicks(time_ticks);
+
+  viewport_rect_for_tile_priority = gfx::Rect(200, 200, 100, 100);
+  transform_for_tile_priority.Translate(100, 100);
+  transform_for_tile_priority.Rotate(45);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport_rect_for_tile_priority,
+                                        transform_for_tile_priority,
+                                        resourceless_software_draw);
+  active_layer_->draw_properties().visible_content_rect = viewport;
+  active_layer_->draw_properties().screen_space_transform = transform;
+  active_layer_->UpdateTiles();
+
+  gfx::Transform screen_to_view(gfx::Transform::kSkipInitialization);
+  bool success = transform_for_tile_priority.GetInverse(&screen_to_view);
+  EXPECT_TRUE(success);
+
+  viewport_rect_for_tile_priority_in_view_space =
+      gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
+          screen_to_view, viewport_rect_for_tile_priority));
+
+  // Verify the viewport rect for tile priority is used in PictureLayerImpl.
+  EXPECT_EQ(active_layer_->viewport_rect_for_tile_priority(),
+            viewport_rect_for_tile_priority_in_view_space);
+
+  // Interset viewport_rect_for_tile_priority_in_view_space with the layer
+  // bounds and the result should be used in PictureLayerTiling.
+  viewport_rect_for_tile_priority_in_view_space.Intersect(
+      gfx::Rect(layer_bounds));
+  tilings = active_layer_->tilings();
+  for (size_t i = 0; i < tilings->num_tilings(); i++) {
+    PictureLayerTiling* tiling = tilings->tiling_at(i);
+    EXPECT_EQ(
+        tiling->GetCurrentVisibleRectForTesting(),
+        gfx::ScaleToEnclosingRect(viewport_rect_for_tile_priority_in_view_space,
+                                  tiling->contents_scale()));
+  }
+}
+
 TEST_F(PictureLayerImplTest, InvalidViewportForPrioritizingTiles) {
   base::TimeTicks time_ticks;
   host_impl_.SetCurrentFrameTimeTicks(time_ticks);
@@ -324,8 +422,12 @@
   bool resourceless_software_draw = false;
   gfx::Rect viewport = gfx::Rect(layer_bounds);
   gfx::Transform transform;
-  host_impl_.SetExternalDrawConstraints(
-      transform, viewport, viewport, resourceless_software_draw);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        transform,
+                                        resourceless_software_draw);
   active_layer_->draw_properties().visible_content_rect = viewport;
   active_layer_->draw_properties().screen_space_transform = transform;
   active_layer_->UpdateTiles();
@@ -333,9 +435,9 @@
   gfx::Rect visible_rect_for_tile_priority =
       active_layer_->visible_rect_for_tile_priority();
   EXPECT_FALSE(visible_rect_for_tile_priority.IsEmpty());
-  gfx::Size viewport_size_for_tile_priority =
-      active_layer_->viewport_size_for_tile_priority();
-  EXPECT_FALSE(viewport_size_for_tile_priority.IsEmpty());
+  gfx::Rect viewport_rect_for_tile_priority =
+      active_layer_->viewport_rect_for_tile_priority();
+  EXPECT_FALSE(viewport_rect_for_tile_priority.IsEmpty());
   gfx::Transform screen_space_transform_for_tile_priority =
       active_layer_->screen_space_transform_for_tile_priority();
 
@@ -348,14 +450,18 @@
   transform.Translate(1.f, 1.f);
   active_layer_->draw_properties().visible_content_rect = viewport;
   active_layer_->draw_properties().screen_space_transform = transform;
-  host_impl_.SetExternalDrawConstraints(
-      transform, viewport, viewport, resourceless_software_draw);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        transform,
+                                        resourceless_software_draw);
   active_layer_->UpdateTiles();
 
   EXPECT_RECT_EQ(visible_rect_for_tile_priority,
                  active_layer_->visible_rect_for_tile_priority());
-  EXPECT_SIZE_EQ(viewport_size_for_tile_priority,
-                 active_layer_->viewport_size_for_tile_priority());
+  EXPECT_RECT_EQ(viewport_rect_for_tile_priority,
+                 active_layer_->viewport_rect_for_tile_priority());
   EXPECT_TRANSFORMATION_MATRIX_EQ(
       screen_space_transform_for_tile_priority,
       active_layer_->screen_space_transform_for_tile_priority());
@@ -364,14 +470,18 @@
   time_ticks += base::TimeDelta::FromMilliseconds(200);
   host_impl_.SetCurrentFrameTimeTicks(time_ticks);
   resourceless_software_draw = false;
-  host_impl_.SetExternalDrawConstraints(
-      transform, viewport, viewport, resourceless_software_draw);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        transform,
+                                        resourceless_software_draw);
   active_layer_->UpdateTiles();
 
   EXPECT_FALSE(visible_rect_for_tile_priority ==
                active_layer_->visible_rect_for_tile_priority());
-  EXPECT_FALSE(viewport_size_for_tile_priority ==
-               active_layer_->viewport_size_for_tile_priority());
+  EXPECT_FALSE(viewport_rect_for_tile_priority ==
+               active_layer_->viewport_rect_for_tile_priority());
   EXPECT_FALSE(screen_space_transform_for_tile_priority ==
                active_layer_->screen_space_transform_for_tile_priority());
 }
@@ -395,8 +505,13 @@
 
   bool resourceless_software_draw = true;
   gfx::Rect viewport = gfx::Rect(layer_bounds);
-  host_impl_.SetExternalDrawConstraints(
-      gfx::Transform(), viewport, viewport, resourceless_software_draw);
+  gfx::Transform identity = gfx::Transform();
+  host_impl_.SetExternalDrawConstraints(identity,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        identity,
+                                        resourceless_software_draw);
   ResetTilingsAndRasterScales();
   host_impl_.pending_tree()->UpdateDrawProperties();
   host_impl_.active_tree()->UpdateDrawProperties();
@@ -2420,8 +2535,12 @@
   bool resourceless_software_draw = false;
   gfx::Rect viewport = gfx::Rect(layer_bounds);
   gfx::Transform transform;
-  host_impl_.SetExternalDrawConstraints(
-      transform, viewport, viewport, resourceless_software_draw);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        transform,
+                                        resourceless_software_draw);
   active_layer_->draw_properties().visible_content_rect = viewport;
   active_layer_->draw_properties().screen_space_transform = transform;
   active_layer_->UpdateTiles();
@@ -2429,9 +2548,9 @@
   gfx::Rect visible_rect_for_tile_priority =
       active_layer_->visible_rect_for_tile_priority();
   EXPECT_FALSE(visible_rect_for_tile_priority.IsEmpty());
-  gfx::Size viewport_size_for_tile_priority =
-      active_layer_->viewport_size_for_tile_priority();
-  EXPECT_FALSE(viewport_size_for_tile_priority.IsEmpty());
+  gfx::Rect viewport_rect_for_tile_priority =
+      active_layer_->viewport_rect_for_tile_priority();
+  EXPECT_FALSE(viewport_rect_for_tile_priority.IsEmpty());
   gfx::Transform screen_space_transform_for_tile_priority =
       active_layer_->screen_space_transform_for_tile_priority();
 
@@ -2444,14 +2563,18 @@
   transform.Translate(1.f, 1.f);
   active_layer_->draw_properties().visible_content_rect = viewport;
   active_layer_->draw_properties().screen_space_transform = transform;
-  host_impl_.SetExternalDrawConstraints(
-      transform, viewport, viewport, resourceless_software_draw);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        transform,
+                                        resourceless_software_draw);
   active_layer_->UpdateTiles();
 
   EXPECT_RECT_EQ(visible_rect_for_tile_priority,
                  active_layer_->visible_rect_for_tile_priority());
-  EXPECT_SIZE_EQ(viewport_size_for_tile_priority,
-                 active_layer_->viewport_size_for_tile_priority());
+  EXPECT_RECT_EQ(viewport_rect_for_tile_priority,
+                 active_layer_->viewport_rect_for_tile_priority());
   EXPECT_TRANSFORMATION_MATRIX_EQ(
       screen_space_transform_for_tile_priority,
       active_layer_->screen_space_transform_for_tile_priority());
@@ -2460,14 +2583,18 @@
   time_ticks += base::TimeDelta::FromMilliseconds(200);
   host_impl_.SetCurrentFrameTimeTicks(time_ticks);
   resourceless_software_draw = false;
-  host_impl_.SetExternalDrawConstraints(
-      transform, viewport, viewport, resourceless_software_draw);
+  host_impl_.SetExternalDrawConstraints(transform,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        transform,
+                                        resourceless_software_draw);
   active_layer_->UpdateTiles();
 
   EXPECT_FALSE(visible_rect_for_tile_priority ==
                active_layer_->visible_rect_for_tile_priority());
-  EXPECT_FALSE(viewport_size_for_tile_priority ==
-               active_layer_->viewport_size_for_tile_priority());
+  EXPECT_FALSE(viewport_rect_for_tile_priority ==
+               active_layer_->viewport_rect_for_tile_priority());
   EXPECT_FALSE(screen_space_transform_for_tile_priority ==
                active_layer_->screen_space_transform_for_tile_priority());
 }
@@ -2491,8 +2618,13 @@
 
   bool resourceless_software_draw = true;
   gfx::Rect viewport = gfx::Rect(layer_bounds);
-  host_impl_.SetExternalDrawConstraints(
-      gfx::Transform(), viewport, viewport, resourceless_software_draw);
+  gfx::Transform identity = gfx::Transform();
+  host_impl_.SetExternalDrawConstraints(identity,
+                                        viewport,
+                                        viewport,
+                                        viewport,
+                                        identity,
+                                        resourceless_software_draw);
   ResetTilingsAndRasterScales();
   host_impl_.pending_tree()->UpdateDrawProperties();
   host_impl_.active_tree()->UpdateDrawProperties();
diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index 4b6b5af..b663a09 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -108,9 +108,15 @@
     const gfx::Transform& transform,
     const gfx::Rect& viewport,
     const gfx::Rect& clip,
+    const gfx::Rect& viewport_rect_for_tile_priority,
+    const gfx::Transform& transform_for_tile_priority,
     bool resourceless_software_draw) {
-  client_->SetExternalDrawConstraints(
-      transform, viewport, clip, resourceless_software_draw);
+  client_->SetExternalDrawConstraints(transform,
+                                      viewport,
+                                      clip,
+                                      viewport_rect_for_tile_priority,
+                                      transform_for_tile_priority,
+                                      resourceless_software_draw);
 }
 
 OutputSurface::~OutputSurface() {
diff --git a/cc/output/output_surface.h b/cc/output/output_surface.h
index 01fdd72..876379c 100644
--- a/cc/output/output_surface.h
+++ b/cc/output/output_surface.h
@@ -167,10 +167,13 @@
   void ReclaimResources(const CompositorFrameAck* ack);
   void DidLoseOutputSurface();
   void SetExternalStencilTest(bool enabled);
-  void SetExternalDrawConstraints(const gfx::Transform& transform,
-                                  const gfx::Rect& viewport,
-                                  const gfx::Rect& clip,
-                                  bool resourceless_software_draw);
+  void SetExternalDrawConstraints(
+      const gfx::Transform& transform,
+      const gfx::Rect& viewport,
+      const gfx::Rect& clip,
+      const gfx::Rect& viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority,
+      bool resourceless_software_draw);
 
  private:
   void SetUpContext3d();
diff --git a/cc/output/output_surface_client.h b/cc/output/output_surface_client.h
index 2c6c128..bb37a91 100644
--- a/cc/output/output_surface_client.h
+++ b/cc/output/output_surface_client.h
@@ -38,10 +38,13 @@
   virtual void DidSwapBuffersComplete() = 0;
   virtual void ReclaimResources(const CompositorFrameAck* ack) = 0;
   virtual void DidLoseOutputSurface() = 0;
-  virtual void SetExternalDrawConstraints(const gfx::Transform& transform,
-                                          const gfx::Rect& viewport,
-                                          const gfx::Rect& clip,
-                                          bool resourceless_software_draw) = 0;
+  virtual void SetExternalDrawConstraints(
+      const gfx::Transform& transform,
+      const gfx::Rect& viewport,
+      const gfx::Rect& clip,
+      const gfx::Rect& viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority,
+      bool resourceless_software_draw) = 0;
   virtual void SetMemoryPolicy(const ManagedMemoryPolicy& policy) = 0;
   // If set, |callback| will be called subsequent to each new tree activation,
   // regardless of the compositor visibility or damage. |callback| must remain
diff --git a/cc/resources/picture_layer_tiling.h b/cc/resources/picture_layer_tiling.h
index fc7505c..79c5900 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -155,6 +155,10 @@
     return all_tiles;
   }
 
+  const gfx::Rect& GetCurrentVisibleRectForTesting() const {
+    return current_visible_rect_in_content_space_;
+  }
+
   // Iterate over all tiles to fill content_rect.  Even if tiles are invalid
   // (i.e. no valid resource) this tiling should still iterate over them.
   // The union of all geometry_rect calls for each element iterated over should
diff --git a/cc/surfaces/display.h b/cc/surfaces/display.h
index 673178b..9139bc0 100644
--- a/cc/surfaces/display.h
+++ b/cc/surfaces/display.h
@@ -57,6 +57,8 @@
       const gfx::Transform& transform,
       const gfx::Rect& viewport,
       const gfx::Rect& clip,
+      const gfx::Rect& viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority,
       bool resourceless_software_draw) OVERRIDE {}
   virtual void SetMemoryPolicy(const ManagedMemoryPolicy& policy) OVERRIDE {}
   virtual void SetTreeActivationCallback(
diff --git a/cc/test/fake_output_surface_client.h b/cc/test/fake_output_surface_client.h
index 5e887b8..7ecb6cf 100644
--- a/cc/test/fake_output_surface_client.h
+++ b/cc/test/fake_output_surface_client.h
@@ -42,6 +42,8 @@
       const gfx::Transform& transform,
       const gfx::Rect& viewport,
       const gfx::Rect& clip,
+      const gfx::Rect& viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority,
       bool resourceless_software_draw) OVERRIDE {}
   virtual void SetMemoryPolicy(const ManagedMemoryPolicy& policy) OVERRIDE;
   virtual void SetTreeActivationCallback(const base::Closure&) OVERRIDE {}
diff --git a/cc/test/fake_picture_layer_impl.h b/cc/test/fake_picture_layer_impl.h
index 04661c4..4cac7ab 100644
--- a/cc/test/fake_picture_layer_impl.h
+++ b/cc/test/fake_picture_layer_impl.h
@@ -78,8 +78,8 @@
   gfx::Rect visible_rect_for_tile_priority() {
     return visible_rect_for_tile_priority_;
   }
-  gfx::Size viewport_size_for_tile_priority() {
-    return viewport_size_for_tile_priority_;
+  gfx::Rect viewport_rect_for_tile_priority() {
+    return viewport_rect_for_tile_priority_;
   }
   gfx::Transform screen_space_transform_for_tile_priority() {
     return screen_space_transform_for_tile_priority_;
diff --git a/cc/test/layer_tree_pixel_test.cc b/cc/test/layer_tree_pixel_test.cc
index f85cac3..74d3819 100644
--- a/cc/test/layer_tree_pixel_test.cc
+++ b/cc/test/layer_tree_pixel_test.cc
@@ -76,8 +76,13 @@
   // Be that influence!
   viewport += gfx::Vector2d(20, 10);
   bool resourceless_software_draw = false;
-  impl->SetExternalDrawConstraints(
-      gfx::Transform(), viewport, viewport, resourceless_software_draw);
+  gfx::Transform identity = gfx::Transform();
+  impl->SetExternalDrawConstraints(identity,
+                                   viewport,
+                                   viewport,
+                                   viewport,
+                                   identity,
+                                   resourceless_software_draw);
   EXPECT_EQ(viewport.ToString(), impl->DeviceViewport().ToString());
 }
 
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 6dd4b3e..5b5d491 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -65,6 +65,7 @@
 #include "cc/trees/tree_synchronizer.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "ui/gfx/frame_time.h"
+#include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/vector2d_conversions.h"
 
@@ -1312,15 +1313,32 @@
     const gfx::Transform& transform,
     const gfx::Rect& viewport,
     const gfx::Rect& clip,
+    const gfx::Rect& viewport_rect_for_tile_priority,
+    const gfx::Transform& transform_for_tile_priority,
     bool resourceless_software_draw) {
+  gfx::Rect viewport_rect_for_tile_priority_in_view_space;
+  if (!resourceless_software_draw) {
+    gfx::Transform screen_to_view(gfx::Transform::kSkipInitialization);
+    if (transform_for_tile_priority.GetInverse(&screen_to_view)) {
+      // Convert from screen space to view space.
+      viewport_rect_for_tile_priority_in_view_space =
+          gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
+              screen_to_view, viewport_rect_for_tile_priority));
+    }
+  }
+
   if (external_transform_ != transform || external_viewport_ != viewport ||
-      resourceless_software_draw_ != resourceless_software_draw) {
+      resourceless_software_draw_ != resourceless_software_draw ||
+      viewport_rect_for_tile_priority_ !=
+          viewport_rect_for_tile_priority_in_view_space) {
     active_tree_->set_needs_update_draw_properties();
   }
 
   external_transform_ = transform;
   external_viewport_ = viewport;
   external_clip_ = clip;
+  viewport_rect_for_tile_priority_ =
+      viewport_rect_for_tile_priority_in_view_space;
   resourceless_software_draw_ = resourceless_software_draw;
 }
 
@@ -2118,6 +2136,13 @@
   SetFullRootLayerDamage();
 }
 
+const gfx::Rect LayerTreeHostImpl::ViewportRectForTilePriority() const {
+  if (viewport_rect_for_tile_priority_.IsEmpty())
+    return DeviceViewport();
+
+  return viewport_rect_for_tile_priority_;
+}
+
 gfx::Size LayerTreeHostImpl::DrawViewportSize() const {
   return DeviceViewport().size();
 }
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index f53001a..d1a6e33 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -219,6 +219,9 @@
   // for draw properties, tilings, quads and render passes.
   gfx::Size DrawViewportSize() const;
 
+  // Viewport rect in view space used for tiling prioritization.
+  const gfx::Rect ViewportRectForTilePriority() const;
+
   // Viewport size for scrolling and fixed-position compensation. This value
   // excludes the URL bar and non-overlay scrollbars and is in DIP (and
   // invariant relative to page scale).
@@ -246,10 +249,13 @@
                                      base::TimeDelta interval) OVERRIDE;
   virtual void SetNeedsRedrawRect(const gfx::Rect& rect) OVERRIDE;
   virtual void BeginFrame(const BeginFrameArgs& args) OVERRIDE;
+
   virtual void SetExternalDrawConstraints(
       const gfx::Transform& transform,
       const gfx::Rect& viewport,
       const gfx::Rect& clip,
+      const gfx::Rect& viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority,
       bool resourceless_software_draw) OVERRIDE;
   virtual void DidLoseOutputSurface() OVERRIDE;
   virtual void DidSwapBuffers() OVERRIDE;
@@ -656,9 +662,12 @@
   // - external_viewport_ is used DrawProperties, tile management and
   // glViewport/window projection matrix.
   // - external_clip_ specifies a top-level clip rect
+  // - viewport_rect_for_tile_priority_ is the rect in view space used for
+  // tiling priority.
   gfx::Transform external_transform_;
   gfx::Rect external_viewport_;
   gfx::Rect external_clip_;
+  gfx::Rect viewport_rect_for_tile_priority_;
   bool resourceless_software_draw_;
 
   gfx::Rect viewport_damage_rect_;
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 4a132cd..fd4261b 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -5572,6 +5572,8 @@
   host_impl_->SetExternalDrawConstraints(external_transform,
                                          external_viewport,
                                          external_clip,
+                                         external_viewport,
+                                         external_transform,
                                          resourceless_software_draw);
 
   EXPECT_EQ(0, software_device->frames_began_);
@@ -5605,6 +5607,8 @@
   host_impl_->SetExternalDrawConstraints(external_transform,
                                          external_viewport,
                                          external_clip,
+                                         external_viewport,
+                                         external_transform,
                                          resourceless_software_draw);
 
   // SolidColorLayerImpl will be drawn.
@@ -6605,6 +6609,10 @@
   host_impl_->SetExternalDrawConstraints(external_transform,
                                          external_viewport,
                                          external_clip,
+                                         external_viewport,
+                                         external_transform,
+                                         external_viewport,
+                                         external_transform,
                                          resourceless_software_draw);
   DrawFrame();
   EXPECT_TRANSFORMATION_MATRIX_EQ(
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 9327257..9ca3308 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -713,10 +713,18 @@
   layer_tree_host_impl_->SetNeedsCommit();
 }
 
+gfx::Rect LayerTreeImpl::DeviceViewport() const {
+  return layer_tree_host_impl_->DeviceViewport();
+}
+
 gfx::Size LayerTreeImpl::DrawViewportSize() const {
   return layer_tree_host_impl_->DrawViewportSize();
 }
 
+const gfx::Rect LayerTreeImpl::ViewportRectForTilePriority() const {
+  return layer_tree_host_impl_->ViewportRectForTilePriority();
+}
+
 scoped_ptr<ScrollbarAnimationController>
 LayerTreeImpl::CreateScrollbarAnimationController(LayerImpl* scrolling_layer) {
   DCHECK(settings().scrollbar_fade_delay_ms);
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 66d1f49..47f3ce1 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -85,7 +85,9 @@
   base::TimeTicks CurrentFrameTimeTicks() const;
   base::TimeDelta begin_impl_frame_interval() const;
   void SetNeedsCommit();
+  gfx::Rect DeviceViewport() const;
   gfx::Size DrawViewportSize() const;
+  const gfx::Rect ViewportRectForTilePriority() const;
   scoped_ptr<ScrollbarAnimationController> CreateScrollbarAnimationController(
       LayerImpl* scrolling_layer);
   void DidAnimateScrollOffset();
diff --git a/content/browser/android/in_process/synchronous_compositor_impl.cc b/content/browser/android/in_process/synchronous_compositor_impl.cc
index 1b5ccb7..f7ac3df 100644
--- a/content/browser/android/in_process/synchronous_compositor_impl.cc
+++ b/content/browser/android/in_process/synchronous_compositor_impl.cc
@@ -124,12 +124,19 @@
     gfx::Size surface_size,
     const gfx::Transform& transform,
     gfx::Rect viewport,
-    gfx::Rect clip) {
+    gfx::Rect clip,
+    gfx::Rect viewport_rect_for_tile_priority,
+    const gfx::Transform& transform_for_tile_priority) {
   DCHECK(CalledOnValidThread());
   DCHECK(output_surface_);
 
   scoped_ptr<cc::CompositorFrame> frame =
-      output_surface_->DemandDrawHw(surface_size, transform, viewport, clip);
+      output_surface_->DemandDrawHw(surface_size,
+                                    transform,
+                                    viewport,
+                                    clip,
+                                    viewport_rect_for_tile_priority,
+                                    transform_for_tile_priority);
   if (frame.get())
     UpdateFrameMetaData(frame->metadata);
   return frame.Pass();
diff --git a/content/browser/android/in_process/synchronous_compositor_impl.h b/content/browser/android/in_process/synchronous_compositor_impl.h
index 6ac80cb..f5cfe96 100644
--- a/content/browser/android/in_process/synchronous_compositor_impl.h
+++ b/content/browser/android/in_process/synchronous_compositor_impl.h
@@ -55,7 +55,9 @@
       gfx::Size surface_size,
       const gfx::Transform& transform,
       gfx::Rect viewport,
-      gfx::Rect clip) OVERRIDE;
+      gfx::Rect clip,
+      gfx::Rect viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority) OVERRIDE;
   virtual bool DemandDrawSw(SkCanvas* canvas) OVERRIDE;
   virtual void ReturnResources(
       const cc::CompositorFrameAck& frame_ack) OVERRIDE;
diff --git a/content/browser/android/in_process/synchronous_compositor_output_surface.cc b/content/browser/android/in_process/synchronous_compositor_output_surface.cc
index 4e8ff8d..6092bd5 100644
--- a/content/browser/android/in_process/synchronous_compositor_output_surface.cc
+++ b/content/browser/android/in_process/synchronous_compositor_output_surface.cc
@@ -162,13 +162,20 @@
     gfx::Size surface_size,
     const gfx::Transform& transform,
     gfx::Rect viewport,
-    gfx::Rect clip) {
+    gfx::Rect clip,
+    gfx::Rect viewport_rect_for_tile_priority,
+    const gfx::Transform& transform_for_tile_priority) {
   DCHECK(CalledOnValidThread());
   DCHECK(HasClient());
   DCHECK(context_provider_);
 
   surface_size_ = surface_size;
-  InvokeComposite(transform, viewport, clip, true);
+  InvokeComposite(transform,
+                  viewport,
+                  clip,
+                  viewport_rect_for_tile_priority,
+                  transform_for_tile_priority,
+                  true);
 
   return frame_holder_.Pass();
 }
@@ -190,7 +197,9 @@
   surface_size_ = gfx::Size(canvas->getDeviceSize().width(),
                             canvas->getDeviceSize().height());
 
-  InvokeComposite(transform, clip, clip, false);
+  // Resourceless software draw does not need viewport_for_tiling.
+  gfx::Rect empty;
+  InvokeComposite(transform, clip, clip, empty, gfx::Transform(), false);
 
   return frame_holder_.Pass();
 }
@@ -199,6 +208,8 @@
     const gfx::Transform& transform,
     gfx::Rect viewport,
     gfx::Rect clip,
+    gfx::Rect viewport_rect_for_tile_priority,
+    gfx::Transform transform_for_tile_priority,
     bool hardware_draw) {
   DCHECK(!invoking_composite_);
   DCHECK(!frame_holder_.get());
@@ -206,8 +217,12 @@
 
   gfx::Transform adjusted_transform = transform;
   AdjustTransform(&adjusted_transform, viewport);
-  SetExternalDrawConstraints(
-      adjusted_transform, viewport, clip, !hardware_draw);
+  SetExternalDrawConstraints(adjusted_transform,
+                             viewport,
+                             clip,
+                             viewport_rect_for_tile_priority,
+                             transform_for_tile_priority,
+                             !hardware_draw);
   SetNeedsRedrawRect(gfx::Rect(viewport.size()));
   client_->BeginFrame(cc::BeginFrameArgs::CreateForSynchronousCompositor());
 
@@ -218,11 +233,16 @@
     cached_hw_transform_ = adjusted_transform;
     cached_hw_viewport_ = viewport;
     cached_hw_clip_ = clip;
+    cached_hw_viewport_rect_for_tile_priority_ =
+        viewport_rect_for_tile_priority;
+    cached_hw_transform_for_tile_priority_ = transform_for_tile_priority;
   } else {
     bool resourceless_software_draw = false;
     SetExternalDrawConstraints(cached_hw_transform_,
                                cached_hw_viewport_,
                                cached_hw_clip_,
+                               cached_hw_viewport_rect_for_tile_priority_,
+                               cached_hw_transform_for_tile_priority_,
                                resourceless_software_draw);
   }
 
diff --git a/content/browser/android/in_process/synchronous_compositor_output_surface.h b/content/browser/android/in_process/synchronous_compositor_output_surface.h
index 2c04ed2..b966ae7 100644
--- a/content/browser/android/in_process/synchronous_compositor_output_surface.h
+++ b/content/browser/android/in_process/synchronous_compositor_output_surface.h
@@ -64,10 +64,13 @@
   bool InitializeHwDraw(
       scoped_refptr<cc::ContextProvider> onscreen_context_provider);
   void ReleaseHwDraw();
-  scoped_ptr<cc::CompositorFrame> DemandDrawHw(gfx::Size surface_size,
-                                               const gfx::Transform& transform,
-                                               gfx::Rect viewport,
-                                               gfx::Rect clip);
+  scoped_ptr<cc::CompositorFrame> DemandDrawHw(
+      gfx::Size surface_size,
+      const gfx::Transform& transform,
+      gfx::Rect viewport,
+      gfx::Rect clip,
+      gfx::Rect viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority);
   void ReturnResources(const cc::CompositorFrameAck& frame_ack);
   scoped_ptr<cc::CompositorFrame> DemandDrawSw(SkCanvas* canvas);
   void SetMemoryPolicy(const SynchronousCompositorMemoryPolicy& policy);
@@ -79,6 +82,8 @@
   void InvokeComposite(const gfx::Transform& transform,
                        gfx::Rect viewport,
                        gfx::Rect clip,
+                       gfx::Rect viewport_rect_for_tile_priority,
+                       gfx::Transform transform_for_tile_priority,
                        bool hardware_draw);
   bool CalledOnValidThread() const;
   SynchronousCompositorOutputSurfaceDelegate* GetDelegate();
@@ -90,6 +95,8 @@
   gfx::Transform cached_hw_transform_;
   gfx::Rect cached_hw_viewport_;
   gfx::Rect cached_hw_clip_;
+  gfx::Rect cached_hw_viewport_rect_for_tile_priority_;
+  gfx::Transform cached_hw_transform_for_tile_priority_;
 
   // Only valid (non-NULL) during a DemandDrawSw() call.
   SkCanvas* current_sw_canvas_;
diff --git a/content/public/browser/android/synchronous_compositor.h b/content/public/browser/android/synchronous_compositor.h
index 62485f1..72c2b19 100644
--- a/content/public/browser/android/synchronous_compositor.h
+++ b/content/public/browser/android/synchronous_compositor.h
@@ -91,7 +91,9 @@
       gfx::Size surface_size,
       const gfx::Transform& transform,
       gfx::Rect viewport,
-      gfx::Rect clip) = 0;
+      gfx::Rect clip,
+      gfx::Rect viewport_rect_for_tile_priority,
+      const gfx::Transform& transform_for_tile_priority) = 0;
 
   // For delegated rendering, return resources from parent compositor to this.
   // Note that all resources must be returned before ReleaseHwDraw.