Don't require VDAs to return all PictureBuffers at once.

media/filters/gpu_video_decoder.h

Index: media/filters/gpu_video_decoder.h
diff --git a/media/filters/gpu_video_decoder.h b/media/filters/gpu_video_decoder.h
index 065ac38d068abecdea8bdc5b769fd6fbec54f915..e81e3d3e8452134af73019413106a3730e67ce47 100644
--- a/media/filters/gpu_video_decoder.h
+++ b/media/filters/gpu_video_decoder.h
@@ -135,9 +135,12 @@ class MEDIA_EXPORT GpuVideoDecoder
   // Destroy all PictureBuffers in |buffers|, and delete their textures.
   void DestroyPictureBuffers(PictureBufferMap* buffers);
 
-  // Returns true if the video decoder can support |profile| and |coded_size|.
-  bool IsProfileSupported(VideoCodecProfile profile,
-                          const gfx::Size& coded_size);
+  // Returns true if the video decoder with |capabilities| can support
+  // |profile| and |coded_size|.
+  bool IsProfileSupported(
+      const VideoDecodeAccelerator::Capabilities& capabilities,
+      VideoCodecProfile profile,
+      const gfx::Size& coded_size);
 
   // Assert the contract that this class is operated on the right thread.
   void DCheckGpuVideoAcceleratorFactoriesTaskRunnerIsCurrent() const;
@@ -203,6 +206,11 @@ class MEDIA_EXPORT GpuVideoDecoder
   // HasAvailableOutputFrames().
   int available_pictures_;
 
+  // If false, then we may assume that the VDA cannot stall sending picture
+  // buffers until all of them have decoded frames.  If true, then it may
+  // stall as long as one picture buffer is outstanding.

[Pawel Osciak, 2015/12/05 00:18:55]

Please clarify what "outstanding" means, where the buffer is, what is its state
(decoded/empty/etc.), etc.

[liberato (no reviews please), 2015/12/07 19:04:39]

done.  please let me know if the new text is more clear.

+  bool can_stall_anytime_;

[Pawel Osciak, 2015/12/05 00:18:55]

What does "anytime" mean? Should we drop it? It's also confusing, since I
believe if can_stall_anytime_ == true and buffers are not allocated, then it
won't stall actually?

[liberato (no reviews please), 2015/12/07 19:04:39]

true, which is why i tried to frame it as "one picture buffer outstanding" in
the docs.  i agree with the sentiment, but couldn't find a shorter name for it. 
suggestions are welcome.

+
   // Bound to factories_->GetMessageLoop().
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<GpuVideoDecoder> weak_factory_;