Don't use fallback frame sinks on Android

content/renderer/gpu/render_widget_compositor.h

 // Copyright (c) 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 CONTENT_RENDERER_GPU_RENDER_WIDGET_COMPOSITOR_H_
 #define CONTENT_RENDERER_GPU_RENDER_WIDGET_COMPOSITOR_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 193 matching lines @@
   void DidCompletePageScaleAnimation() override;
   bool IsForSubframe() override;
 
   // cc::LayerTreeHostSingleThreadClient implementation.
   void RequestScheduleAnimation() override;
   void DidSubmitCompositorFrame() override;
   void DidLoseCompositorFrameSink() override;
 
   enum {
     COMPOSITOR_FRAME_SINK_RETRIES_BEFORE_FALLBACK = 4,
+#ifdef OS_ANDROID
+    // On Android, we don't use fallback frame sinks. (crbug.com/721102)

[enne (OOO), 2017/05/12 16:46:59]

This is a little subtle, and I think folks looking at rwc.cc won't realize that
Android never has a fallback. Could you add a #ifdef OS_ANDROID and
LOG_IF(FATAL, ...) in RWC::RequestNewCompositorFrameSink if fallback is true?

[Saman Sami, 2017/05/12 17:12:45]

Done.

+    MAX_COMPOSITOR_FRAME_SINK_RETRIES = 4,
+#else
     MAX_COMPOSITOR_FRAME_SINK_RETRIES = 5,
+#endif
   };
 
  protected:
   friend class RenderViewImplScaleFactorTest;
 
   RenderWidgetCompositor(RenderWidgetCompositorDelegate* delegate,
                          CompositorDependencies* compositor_deps);
 
   cc::LayerTreeHost* layer_tree_host() { return layer_tree_host_.get(); }
 
@@ skipping 19 matching lines @@
   cc::FrameSinkId frame_sink_id_;
 
   base::WeakPtrFactory<RenderWidgetCompositor> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetCompositor);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_GPU_RENDER_WIDGET_COMPOSITOR_H_