Paint first frame faster, don't crash with no frames during EOS.

media/base/video_frame.h

 // Copyright (c) 2012 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 MEDIA_BASE_VIDEO_FRAME_H_
 #define MEDIA_BASE_VIDEO_FRAME_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 402 matching lines @@
 
   // It uses |client| to insert a new sync point and potentially waits on a
   // older sync point. The final sync point will be used to release this
   // VideoFrame.
   // This method is thread safe. Both blink and compositor threads can call it.
   void UpdateReleaseSyncToken(SyncTokenClient* client);
 
   // Returns a human-readable string describing |*this|.
   std::string AsHumanReadableString();
 
+  // Unique identifier for this video frame; generated at construction time and
+  // guaranteed to be unique within a single process.
+  int unique_id() const { return unique_id_; }
+
  protected:
   friend class base::RefCountedThreadSafe<VideoFrame>;
 
   // Clients must use the static factory/wrapping methods to create a new frame.
   // Derived classes should create their own factory/wrapping methods, and use
   // this constructor to do basic initialization.
   VideoFrame(VideoPixelFormat format,
              StorageType storage_type,
              const gfx::Size& coded_size,
              const gfx::Rect& visible_rect,
@@ skipping 129 matching lines @@
 
   std::vector<base::Closure> done_callbacks_;
 
   base::TimeDelta timestamp_;
 
   base::Lock release_sync_token_lock_;
   gpu::SyncToken release_sync_token_;
 
   VideoFrameMetadata metadata_;
 
+  // Generated at construction time.
+  const int unique_id_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(VideoFrame);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_FRAME_H_