[Android] Fix a flicker in stopping Chrome

chrome/android/java/src/org/chromium/chrome/browser/Tab.java

Index: chrome/android/java/src/org/chromium/chrome/browser/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
index 2cc653a9ecb0b14ca0359e2f02aaf8ceb7e2ef22..c4804519ae1a20fcad35e03fb25b9ef4479c104e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
@@ -8,6 +8,7 @@ import android.app.Activity;
 import android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.Color;
+import android.os.Handler;
 import android.text.TextUtils;
 import android.util.Log;
 import android.view.ContextMenu;
@@ -271,6 +272,8 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
      */
     private View mSadTabView;
 
+    private boolean mStarted;
+
     /**
      * A default {@link ChromeContextMenuItemDelegate} that supports some of the context menu
      * functionality.
@@ -1065,6 +1068,7 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
      * on both cold and warm starts.
      */
     public void onActivityStart() {
+        mStarted = true;
         show(TabSelectionType.FROM_USER);
 
         // When resuming the activity, force an update to the fullscreen state to ensure a
@@ -1077,7 +1081,15 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
      * Called on the foreground tab when the Activity is stopped.
      */
     public void onActivityStop() {
-        hide();
+        // Delay hiding in order to avoid a white flicker in closing an activity.
+        mStarted = false;
+        final Handler handler = new Handler();
+        handler.postDelayed(new Runnable() {
+            @Override
+            public void run() {
+                if (!mStarted) hide();
+            }
+        }, 500);

[David Trainor- moved to gerrit, 2015/01/09 18:07:52]

Does this only happen on L and above?  Should we only do it on those devices? 
Hmm I wonder if there's a callback for when we actually finish the animation so
we know the exact time to hide.

     }
 
     /**