Make the video layer contents visible in OverlayFullscreenVideo mode

content/renderer/media/android/webmediaplayer_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 CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIAPLAYER_ANDROID_H_
 #define CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIAPLAYER_ANDROID_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 329 matching lines @@
   // Size of the video.
   blink::WebSize natural_size_;
 
   // Size that has been sent to gpu::StreamTexture.
   blink::WebSize cached_stream_texture_size_;
 
   // The video frame object used for rendering by the compositor.
   scoped_refptr<media::VideoFrame> current_frame_;
   base::Lock current_frame_lock_;
 
+  // A lazily created transparent video frame to be displayed in fullscreen.
+  scoped_refptr<media::VideoFrame> fullscreen_frame_;

[qinmin, 2016/04/21 16:33:11]

why cannot we just use current_frame_?

[watk, 2016/04/21 18:56:28]

Well, it's a strange case. VideoResourceUpdater, which is used by the
compositor, asserts that each new VideoFrame it see have unique timestamps in
debug mode.. So that was DCHECKing when I created a new fullscreen frame each
time because they all had timestamp 0. So we could either:

a) change VideoResourceUpdater to not require that. Larger change and not clear
how to keep the useful behavior of catching bugs for normal playbacks where the
timestamps should be unique.
b) give fullscreen frames a dummy timestamp. Ugly and weird.
c) only ever create one fullscreen frame. Seemed like a reasonable thing to do
anyway as a micro optimization and it should use very 
little memory because it's a 1x1 image.

+
   base::ThreadChecker main_thread_checker_;
 
   // Message loop for media thread.
   const scoped_refptr<base::SingleThreadTaskRunner> media_task_runner_;
 
   // URL of the media file to be fetched.
   GURL url_;
 
   // URL of the media file after |media_info_loader_| resolves all the
   // redirections.
@@ skipping 155 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<WebMediaPlayerAndroid> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIAPLAYER_ANDROID_H_