Always support pack/unpack row length on ES3. Add support for NV_pack_subimage extension.

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://chromiumcodereview.appspot.com/23003009

git-svn-id: http://skia.googlecode.com/svn/trunk/src@10778 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/gl/GrGLCaps.cpp b/gpu/gl/GrGLCaps.cpp
index 61ef852..5ddf21c 100644
--- a/gpu/gl/GrGLCaps.cpp
+++ b/gpu/gl/GrGLCaps.cpp
@@ -147,10 +147,11 @@
         fPackRowLengthSupport = true;
         fPackFlipYSupport = false;
     } else {
-        fUnpackRowLengthSupport =ctxInfo.hasExtension("GL_EXT_unpack_subimage");
+        fUnpackRowLengthSupport = version >= GR_GL_VER(3,0) ||
+                                  ctxInfo.hasExtension("GL_EXT_unpack_subimage");
         fUnpackFlipYSupport = ctxInfo.hasExtension("GL_CHROMIUM_flipy");
-        // no extension for pack row length
-        fPackRowLengthSupport = false;
+        fPackRowLengthSupport = version >= GR_GL_VER(3,0) ||
+                                ctxInfo.hasExtension("GL_NV_pack_subimage");
         fPackFlipYSupport =
             ctxInfo.hasExtension("GL_ANGLE_pack_reverse_row_order");
     }