media: Fix a GpuVideoDecoder initialization crash on Android

media/filters/gpu_video_decoder.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_FILTERS_GPU_VIDEO_DECODER_H_
 #define MEDIA_FILTERS_GPU_VIDEO_DECODER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 160 matching lines @@
   // For requesting a suface to render to. If this is null the VDA will return
   // normal video frames and not render them to a surface.
   RequestSurfaceCB request_surface_cb_;
 
   scoped_refptr<MediaLog> media_log_;
 
   // Populated during Initialize() (on success) and unchanged until an error
   // occurs.
   std::unique_ptr<VideoDecodeAccelerator> vda_;
 
+  // Whether |vda_->Initialize()| has been called.

[sandersd (OOO until July 31), 2017/01/11 21:39:58]

This is accurate, but hard to interpret with regards to the async initialize
process. Recommend expanding this text to explain that in more detail.

+  bool vda_initialized_;
+
   InitCB init_cb_;
   OutputCB output_cb_;
 
   DecodeCB eos_decode_cb_;
 
   // Not null only during reset.
   base::Closure pending_reset_cb_;
 
   State state_;
 
@@ skipping 67 matching lines @@
   // Bound to factories_->GetMessageLoop().
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<GpuVideoDecoder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuVideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_GPU_VIDEO_DECODER_H_