Avoid waiting on the SurfaceTexture until we need to.

media/gpu/avda_shared_state.h

 // Copyright 2015 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_COMMON_GPU_AVDA_SHARED_STATE_H_
-#define CONTENT_COMMON_GPU_AVDA_SHARED_STATE_H_
+#ifndef MEDIA_GPU_AVDA_SHARED_STATE_H_
+#define MEDIA_GPU_AVDA_SHARED_STATE_H_
 
 #include "base/synchronization/waitable_event.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 #include "media/base/android/media_codec_bridge.h"
 #include "media/base/android/sdk_media_codec_bridge.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_image.h"
 #include "ui/gl/gl_surface.h"
 
 namespace gfx {
@@ skipping 53 matching lines @@
 
   // Call this when the SurfaceTexture is attached to a GL context.  This will
   // update surface_texture_is_attached(), and set the context() and surface()
   // to match.
   void DidAttachSurfaceTexture();
 
   // Call this when the SurfaceTexture is detached from its GL context.  This
   // will cause us to forget the last binding.
   void DidDetachSurfaceTexture();
 
+  // Helper method for coordinating the interactions between
+  // MediaCodec::ReleaseOutputBuffer() and WaitForFrameAvailable() when
+  // rendering to a SurfaceTexture; this method should never be called when
+  // rendering to a SurfaceView.
+  //
+  // The release of the codec buffer to the surface texture is asynchronous, by
+  // using this helper we can attempt to let this process complete in a non
+  // blocking fashion before the SurfaceTexture is used.
+  //
+  // Clients should call this method to release the codec buffer for rendering
+  // and then call WaitForFrameAvailable() before using the SurfaceTexture. In
+  // the ideal case the SurfaceTexture has already been updated, otherwise the
+  // method will wait for a pro-rated amount of time based on elapsed time up
+  // to a short deadline.
+  //
+  // Some devices do not reliably notify frame availability, so we use a very
+  // short deadline of only a few milliseconds to avoid indefinite stalls.
+  void RenderCodecBufferToSurfaceTexture(media::MediaCodecBridge* codec,
+                                         int codec_buffer_index);
+
  protected:
   virtual ~AVDASharedState();
 
  private:
   friend class base::RefCounted<AVDASharedState>;
 
   // Platform gl texture Id for |surface_texture_|.  This will be zero if
   // and only if |texture_owner_| is null.
   // TODO(liberato): This should be GLuint, but we don't seem to have the type.
   GLint surface_texture_service_id_;
 
   // For signalling OnFrameAvailable().
   base::WaitableEvent frame_available_event_;
 
   // True if and only if the surface texture is currently attached.
   bool surface_texture_is_attached_;
 
   // Context and surface that the surface texture is attached to, if it is
   // currently attached.
   scoped_refptr<gfx::GLContext> context_;
   scoped_refptr<gfx::GLSurface> surface_;
 
   // Maps a picture buffer id to a AVDACodecImage.
   std::map<int, AVDACodecImage*> codec_images_;
 
+  // The time of the last call to RenderCodecBufferToSurfaceTexture(), null if
+  // there has been no last call.

[liberato (no reviews please), 2016/05/03 05:49:30]

not quite accurate -- null if and only if a frame available signal is expected
but not waited for.

[DaleCurtis, 2016/05/04 00:25:29]

Actually, I think your suggestion isn't accurate :) I think it's missing a "not"
at the beginning. In any case I've added some verbosity here which should make
this clearer.

+  base::TimeTicks release_time_;
+
   DISALLOW_COPY_AND_ASSIGN(AVDASharedState);
 };
 
 }  // namespace media
 
-#endif  // CONTENT_COMMON_GPU_AVDA_SHARED_STATE_H_
+#endif  // MEDIA_GPU_AVDA_SHARED_STATE_H_