diff --git a/api/system-current.txt b/api/system-current.txt
index a2c2771..74a2bae 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -120,6 +120,7 @@
     field public static final java.lang.String GRANT_RUNTIME_PERMISSIONS = "android.permission.GRANT_RUNTIME_PERMISSIONS";
     field public static final java.lang.String HARDWARE_TEST = "android.permission.HARDWARE_TEST";
     field public static final java.lang.String HDMI_CEC = "android.permission.HDMI_CEC";
+    field public static final java.lang.String HIDE_NON_SYSTEM_OVERLAY_WINDOWS = "android.permission.HIDE_NON_SYSTEM_OVERLAY_WINDOWS";
     field public static final java.lang.String INJECT_EVENTS = "android.permission.INJECT_EVENTS";
     field public static final java.lang.String INSTALL_GRANT_RUNTIME_PERMISSIONS = "android.permission.INSTALL_GRANT_RUNTIME_PERMISSIONS";
     field public static final java.lang.String INSTALL_LOCATION_PROVIDER = "android.permission.INSTALL_LOCATION_PROVIDER";
diff --git a/core/java/android/view/WindowManager.java b/core/java/android/view/WindowManager.java
index 4060b9a..c1e8f1c 100644
--- a/core/java/android/view/WindowManager.java
+++ b/core/java/android/view/WindowManager.java
@@ -1380,15 +1380,13 @@
         public static final int PRIVATE_FLAG_SUSTAINED_PERFORMANCE_MODE = 0x00040000;
 
         /**
-         * Flag to indicate that this window is used as a task snapshot window. A task snapshot
-         * window is a starting window that gets shown with a screenshot from the previous state
-         * that is active until the app has drawn its first frame.
-         *
-         * <p>If this flag is set, SystemUI flags are ignored such that the real window behind can
-         * set the SystemUI flags.
+         * Flag to indicate that any window added by an application process that is of type
+         * {@link #TYPE_TOAST} or that requires
+         * {@link android.app.AppOpsManager#OP_SYSTEM_ALERT_WINDOW} permission should be hidden when
+         * this window is visible.
          * @hide
          */
-        public static final int PRIVATE_FLAG_TASK_SNAPSHOT = 0x00080000;
+        public static final int PRIVATE_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS = 0x00080000;
 
         /**
          * Control flags that are private to the platform.
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 794d4f8..b2a7363 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -2333,6 +2333,15 @@
     <permission android:name="android.permission.INTERNAL_SYSTEM_WINDOW"
         android:protectionLevel="signature" />
 
+    <!-- @SystemApi Allows an application to use
+         {@link android.view.WindowManager.LayoutsParams#PRIVATE_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS}
+         to hide non-system-overlay windows.
+         <p>Not for use by third-party applications.
+         @hide
+    -->
+    <permission android:name="android.permission.HIDE_NON_SYSTEM_OVERLAY_WINDOWS"
+                android:protectionLevel="signature|installer" />
+
     <!-- @SystemApi Allows an application to manage (create, destroy,
          Z-order) application tokens in the window manager.
          <p>Not for use by third-party applications.
diff --git a/services/core/java/com/android/server/wm/Session.java b/services/core/java/com/android/server/wm/Session.java
index 7e575bf..74f644c 100644
--- a/services/core/java/com/android/server/wm/Session.java
+++ b/services/core/java/com/android/server/wm/Session.java
@@ -16,6 +16,7 @@
 
 package com.android.server.wm;
 
+import static android.Manifest.permission.HIDE_NON_SYSTEM_OVERLAY_WINDOWS;
 import static android.Manifest.permission.INTERNAL_SYSTEM_WINDOW;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.os.Trace.TRACE_TAG_WINDOW_MANAGER;
@@ -82,6 +83,7 @@
     // Set of visible alert window surfaces connected to this session.
     private final Set<WindowSurfaceController> mAlertWindowSurfaces = new HashSet<>();
     final boolean mCanAddInternalSystemWindow;
+    final boolean mCanHideNonSystemOverlayWindows;
     private AlertWindowNotification mAlertWindowNotification;
     private boolean mShowingAlertWindowNotificationAllowed;
     private boolean mClientDead = false;
@@ -99,6 +101,8 @@
         mLastReportedAnimatorScale = service.getCurrentAnimatorScale();
         mCanAddInternalSystemWindow = service.mContext.checkCallingOrSelfPermission(
                 INTERNAL_SYSTEM_WINDOW) == PERMISSION_GRANTED;
+        mCanHideNonSystemOverlayWindows = service.mContext.checkCallingOrSelfPermission(
+                HIDE_NON_SYSTEM_OVERLAY_WINDOWS) == PERMISSION_GRANTED;
         mShowingAlertWindowNotificationAllowed = mService.mShowAlertWindowNotifications;
         StringBuilder sb = new StringBuilder();
         sb.append("Session{");
diff --git a/services/core/java/com/android/server/wm/TaskSnapshotSurface.java b/services/core/java/com/android/server/wm/TaskSnapshotSurface.java
index a96d224..249620131 100644
--- a/services/core/java/com/android/server/wm/TaskSnapshotSurface.java
+++ b/services/core/java/com/android/server/wm/TaskSnapshotSurface.java
@@ -32,7 +32,6 @@
 import static android.view.WindowManager.LayoutParams.FLAG_SPLIT_TOUCH;
 import static android.view.WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_FORCE_DRAW_STATUS_BAR_BACKGROUND;
-import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_TASK_SNAPSHOT;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_STARTING;
 import static com.android.internal.policy.DecorView.NAVIGATION_BAR_COLOR_VIEW_ATTRIBUTES;
 import static com.android.internal.policy.DecorView.STATUS_BAR_COLOR_VIEW_ATTRIBUTES;
@@ -164,8 +163,7 @@
             layoutParams.flags = (windowFlags & ~FLAG_INHERIT_EXCLUDES)
                     | FLAG_NOT_FOCUSABLE
                     | FLAG_NOT_TOUCHABLE;
-            layoutParams.privateFlags = PRIVATE_FLAG_TASK_SNAPSHOT
-                    | (windowPrivateFlags & PRIVATE_FLAG_INHERITS);
+            layoutParams.privateFlags = windowPrivateFlags & PRIVATE_FLAG_INHERITS;
             layoutParams.token = token.token;
             layoutParams.width = LayoutParams.MATCH_PARENT;
             layoutParams.height = LayoutParams.MATCH_PARENT;
diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 7a91d1e..f236b5a 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -28,7 +28,6 @@
 import static android.os.Process.ROOT_UID;
 import static android.os.Process.SHELL_UID;
 import static android.os.Process.SYSTEM_UID;
-import static android.os.Process.THREAD_PRIORITY_DISPLAY;
 import static android.os.Process.myPid;
 import static android.os.Trace.TRACE_TAG_WINDOW_MANAGER;
 import static android.os.UserHandle.USER_NULL;
@@ -48,7 +47,6 @@
 import static android.view.WindowManager.LayoutParams.LAST_APPLICATION_WINDOW;
 import static android.view.WindowManager.LayoutParams.LAST_SUB_WINDOW;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_COMPATIBLE_WINDOW;
-import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_TASK_SNAPSHOT;
 import static android.view.WindowManager.LayoutParams.TYPE_ACCESSIBILITY_OVERLAY;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_STARTING;
 import static android.view.WindowManager.LayoutParams.TYPE_DOCK_DIVIDER;
@@ -228,7 +226,6 @@
 import com.android.server.EventLogTags;
 import com.android.server.FgThread;
 import com.android.server.LocalServices;
-import com.android.server.ThreadPriorityBooster;
 import com.android.server.UiThread;
 import com.android.server.Watchdog;
 import com.android.server.input.InputManagerService;
@@ -493,12 +490,15 @@
      */
     Runnable mWaitingForDrawnCallback;
 
+    /** List of window currently causing non-system overlay windows to be hidden. */
+    private ArrayList<WindowState> mHidingNonSystemOverlayWindows = new ArrayList<>();
+
     /**
      * Stores for each user whether screencapture is disabled
      * This array is essentially a cache for all userId for
      * {@link android.app.admin.DevicePolicyManager#getScreenCaptureDisabled}
      */
-    SparseArray<Boolean> mScreenCaptureDisabled = new SparseArray<>();
+    private SparseArray<Boolean> mScreenCaptureDisabled = new SparseArray<>();
 
     IInputMethodManager mInputMethodManager;
 
@@ -1435,6 +1435,9 @@
                 }
             }
 
+            final boolean hideSystemAlertWindows = !mHidingNonSystemOverlayWindows.isEmpty();
+            win.setForceHideNonSystemOverlayWindowIfNeeded(hideSystemAlertWindows);
+
             final AppWindowToken aToken = token.asAppWindowToken();
             if (type == TYPE_APPLICATION_STARTING && aToken != null) {
                 aToken.startingWindow = win;
@@ -1708,6 +1711,7 @@
         }
         mPendingRemove.remove(win);
         mResizingWindows.remove(win);
+        updateNonSystemOverlayWindowsVisibilityIfNeeded(win, false /* surfaceShown */);
         mWindowsChanged = true;
         if (DEBUG_WINDOW_MOVEMENT) Slog.v(TAG_WM, "Final remove of window: " + win);
 
@@ -6414,6 +6418,21 @@
             ArrayList<WindowState> windows) {
         mRoot.dumpWindowsNoHeader(pw, dumpAll, windows);
 
+        if (!mHidingNonSystemOverlayWindows.isEmpty()) {
+            pw.println();
+            pw.println("  Hiding System Alert Windows:");
+            for (int i = mHidingNonSystemOverlayWindows.size() - 1; i >= 0; i--) {
+                final WindowState w = mHidingNonSystemOverlayWindows.get(i);
+                pw.print("  #"); pw.print(i); pw.print(' ');
+                pw.print(w);
+                if (dumpAll) {
+                    pw.println(":");
+                    w.dump(pw, "    ", true);
+                } else {
+                    pw.println();
+                }
+            }
+        }
         if (mPendingRemove.size() > 0) {
             pw.println();
             pw.println("  Remove pending for:");
@@ -7519,4 +7538,28 @@
             }
         }
     }
+
+    void updateNonSystemOverlayWindowsVisibilityIfNeeded(WindowState win, boolean surfaceShown) {
+        if (!win.hideNonSystemOverlayWindowsWhenVisible()) {
+            return;
+        }
+        final boolean systemAlertWindowsHidden = !mHidingNonSystemOverlayWindows.isEmpty();
+        if (surfaceShown) {
+            if (!mHidingNonSystemOverlayWindows.contains(win)) {
+                mHidingNonSystemOverlayWindows.add(win);
+            }
+        } else {
+            mHidingNonSystemOverlayWindows.remove(win);
+        }
+
+        final boolean hideSystemAlertWindows = !mHidingNonSystemOverlayWindows.isEmpty();
+
+        if (systemAlertWindowsHidden == hideSystemAlertWindows) {
+            return;
+        }
+
+        mRoot.forAllWindows((w) -> {
+            w.setForceHideNonSystemOverlayWindowIfNeeded(hideSystemAlertWindows);
+        }, false /* traverseTopToBottom */);
+    }
 }
diff --git a/services/core/java/com/android/server/wm/WindowState.java b/services/core/java/com/android/server/wm/WindowState.java
index f74948f..b3f0a43 100644
--- a/services/core/java/com/android/server/wm/WindowState.java
+++ b/services/core/java/com/android/server/wm/WindowState.java
@@ -46,6 +46,7 @@
 import static android.view.WindowManager.LayoutParams.LAST_SUB_WINDOW;
 import static android.view.WindowManager.LayoutParams.MATCH_PARENT;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_COMPATIBLE_WINDOW;
+import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_LAYOUT_CHILD_WINDOW_IN_PARENT_FRAME;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_NO_MOVE_ANIMATION;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_WILL_NOT_REPLACE_ON_RELAUNCH;
@@ -59,7 +60,9 @@
 import static android.view.WindowManager.LayoutParams.TYPE_DRAWN_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_INPUT_METHOD;
 import static android.view.WindowManager.LayoutParams.TYPE_INPUT_METHOD_DIALOG;
+import static android.view.WindowManager.LayoutParams.TYPE_TOAST;
 import static android.view.WindowManager.LayoutParams.TYPE_WALLPAPER;
+import static android.view.WindowManager.LayoutParams.isSystemAlertWindowType;
 import static android.view.WindowManagerGlobal.RELAYOUT_RES_DRAG_RESIZING_DOCKED;
 import static android.view.WindowManagerGlobal.RELAYOUT_RES_DRAG_RESIZING_FREEFORM;
 import static android.view.WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME;
@@ -208,6 +211,8 @@
     boolean mPolicyVisibilityAfterAnim = true;
     private boolean mAppOpVisibility = true;
     boolean mPermanentlyHidden; // the window should never be shown again
+    // This is a non-system overlay window that is currently force hidden.
+    private boolean mForceHideNonSystemOverlayWindow;
     boolean mAppFreezing;
     boolean mHidden;    // Used to determine if to show child windows.
     boolean mWallpaperVisible;  // for wallpaper, what was last vis report?
@@ -2371,6 +2376,10 @@
             // to handle their windows being removed from under them.
             return false;
         }
+        if (mForceHideNonSystemOverlayWindow) {
+            // This is an alert window that is currently force hidden.
+            return false;
+        }
         if (mPolicyVisibility && mPolicyVisibilityAfterAnim) {
             // Already showing.
             return false;
@@ -2447,6 +2456,22 @@
         return true;
     }
 
+    void setForceHideNonSystemOverlayWindowIfNeeded(boolean forceHide) {
+        if (mOwnerCanAddInternalSystemWindow
+                || (!isSystemAlertWindowType(mAttrs.type) && mAttrs.type != TYPE_TOAST)) {
+            return;
+        }
+        if (mForceHideNonSystemOverlayWindow == forceHide) {
+            return;
+        }
+        mForceHideNonSystemOverlayWindow = forceHide;
+        if (forceHide) {
+            hideLw(true /* doAnimation */, true /* requestAnim */);
+        } else {
+            showLw(true /* doAnimation */, true /* requestAnim */);
+        }
+    }
+
     public void setAppOpVisibilityLw(boolean state) {
         if (mAppOpVisibility != state) {
             mAppOpVisibility = state;
@@ -3330,7 +3355,7 @@
             pw.println(Integer.toHexString(mSystemUiVisibility));
         }
         if (!mPolicyVisibility || !mPolicyVisibilityAfterAnim || !mAppOpVisibility
-                || isParentWindowHidden()|| mPermanentlyHidden) {
+                || isParentWindowHidden()|| mPermanentlyHidden || mForceHideNonSystemOverlayWindow) {
             pw.print(prefix); pw.print("mPolicyVisibility=");
                     pw.print(mPolicyVisibility);
                     pw.print(" mPolicyVisibilityAfterAnim=");
@@ -3338,8 +3363,8 @@
                     pw.print(" mAppOpVisibility=");
                     pw.print(mAppOpVisibility);
                     pw.print(" parentHidden="); pw.print(isParentWindowHidden());
-                    pw.print(" mPermanentlyHidden="); pw.println(mPermanentlyHidden);
-        }
+                    pw.print(" mForceHideNonSystemOverlayWindow="); pw.println(
+                    mForceHideNonSystemOverlayWindow);        }
         if (!mRelayoutCalled || mLayoutNeeded) {
             pw.print(prefix); pw.print("mRelayoutCalled="); pw.print(mRelayoutCalled);
                     pw.print(" mLayoutNeeded="); pw.println(mLayoutNeeded);
@@ -3593,6 +3618,17 @@
                 && (mAttrs.privateFlags & PRIVATE_FLAG_LAYOUT_CHILD_WINDOW_IN_PARENT_FRAME) != 0;
     }
 
+    /**
+     * Returns true if any window added by an application process that if of type
+     * {@link android.view.WindowManager.LayoutParams#TYPE_TOAST} or that requires that requires
+     * {@link android.app.AppOpsManager#OP_SYSTEM_ALERT_WINDOW} permission should be hidden when
+     * this window is visible.
+     */
+    boolean hideNonSystemOverlayWindowsWhenVisible() {
+        return (mAttrs.privateFlags & PRIVATE_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS) != 0
+                && mSession.mCanHideNonSystemOverlayWindows;
+    }
+
     /** Returns the parent window if this is a child of another window, else null. */
     WindowState getParentWindow() {
         // NOTE: We are not calling getParent() directly as the WindowState might be a child of a
diff --git a/services/core/java/com/android/server/wm/WindowSurfaceController.java b/services/core/java/com/android/server/wm/WindowSurfaceController.java
index 27927e6..1728cfb 100644
--- a/services/core/java/com/android/server/wm/WindowSurfaceController.java
+++ b/services/core/java/com/android/server/wm/WindowSurfaceController.java
@@ -24,10 +24,8 @@
 import static com.android.server.wm.WindowManagerDebugConfig.DEBUG_VISIBILITY;
 import static com.android.server.wm.WindowManagerDebugConfig.TAG_WITH_CLASS_NAME;
 import static com.android.server.wm.WindowManagerDebugConfig.TAG_WM;
-import static android.view.Surface.SCALING_MODE_FREEZE;
 import static android.view.Surface.SCALING_MODE_SCALE_TO_WINDOW;
 
-import android.graphics.PixelFormat;
 import android.graphics.Point;
 import android.graphics.PointF;
 import android.graphics.Rect;
@@ -514,6 +512,8 @@
     void setShown(boolean surfaceShown) {
         mSurfaceShown = surfaceShown;
 
+        mService.updateNonSystemOverlayWindowsVisibilityIfNeeded(mAnimator.mWin, surfaceShown);
+
         if (mWindowSession != null) {
             mWindowSession.onWindowSurfaceVisibilityChanged(this, mSurfaceShown, mWindowType);
         }