Hide fullscreen rotation jank

ui/android/view_android.h

 // Copyright 2013 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 UI_ANDROID_VIEW_ANDROID_H_
 #define UI_ANDROID_VIEW_ANDROID_H_
 
 #include <list>
 
 #include "base/android/jni_array.h"
@@ skipping 112 matching lines @@
   // Moves the give child ViewAndroid to the front of the list so that it can be
   // the first responder of events.
   void MoveToFront(ViewAndroid* child);
 
   // Detaches this view from its parent.
   void RemoveFromParent();
 
   // Sets the layout relative to parent. Used to do hit testing against events.
   void SetLayout(LayoutParams params);
 
+  void ClearThumbnailPlaceholder();

[boliu, 2017/07/05 17:39:48]

this has nothing to do with ViewAndroid tree

and feels like a layering violation too, since thumbnail placeholder is an
entirely chrome/ concept, so lower layers like content/ or ui/ should not know
about it.

shouldn't chrome layer know to do this already, whenever it enters fullscreen?
If that doesn't work, then need to name this to "what happened" rather than "do
this", maybe something like DidEvictFrameForFullscreenTransition

+
   bool StartDragAndDrop(const base::android::JavaRef<jstring>& jtext,
                         const base::android::JavaRef<jobject>& jimage);
 
   gfx::Size GetPhysicalBackingSize();
   void OnPhysicalBackingSizeChanged(const gfx::Size& size);
   void OnBackgroundColorChanged(unsigned int color);
   void OnTopControlsChanged(float top_controls_offset,
                             float top_content_offset);
   void OnBottomControlsChanged(float bottom_controls_offset,
                                float bottom_content_offset);
@@ skipping 85 matching lines @@
   float content_offset_;      // y content offset from the top.
 
   std::unique_ptr<EventForwarder> event_forwarder_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewAndroid);
 };
 
 }  // namespace ui
 
 #endif  // UI_ANDROID_VIEW_ANDROID_H_