ReleaseOutputBuffer to surface back and front buffers where possible.

content/common/gpu/media/android_video_decode_accelerator.h

Index: content/common/gpu/media/android_video_decode_accelerator.h
diff --git a/content/common/gpu/media/android_video_decode_accelerator.h b/content/common/gpu/media/android_video_decode_accelerator.h
index 9e0d8ab9546e02b2818074abe01c6e3af95fb9c9..5c0af106c9b99a66509abece354069046bca1413 100644
--- a/content/common/gpu/media/android_video_decode_accelerator.h
+++ b/content/common/gpu/media/android_video_decode_accelerator.h
@@ -76,7 +76,8 @@ class CONTENT_EXPORT AndroidVideoDecodeAccelerator
     // the decoded output buffer at codec_buffer_index.
     virtual void UseCodecBufferForPictureBuffer(
         int32_t codec_buffer_index,
-        const media::PictureBuffer& picture_buffer) = 0;
+        const media::PictureBuffer& picture_buffer,
+        const std::vector<int32_t>& pictures_out_for_display) = 0;

[liberato (no reviews please), 2016/04/22 00:51:05]

couldn't pictures_out_for_display be an implementation detail of the deferred
strategy, rather than passing it around?  i think that it gets all the callbacks
that it needs to keep it up to date.

[DaleCurtis, 2016/04/22 01:33:58]

Great suggestion. Done.

 
     // Notify strategy that a picture buffer has been assigned.
     virtual void AssignOnePictureBuffer(
@@ -85,7 +86,12 @@ class CONTENT_EXPORT AndroidVideoDecodeAccelerator
 
     // Notify strategy that a picture buffer has been reused.
     virtual void ReuseOnePictureBuffer(
-        const media::PictureBuffer& picture_buffer) {}
+        const media::PictureBuffer& picture_buffer,
+        const std::vector<int32_t>& pictures_out_for_display) {}
+
+    // Attempts to free up codec output buffers by rendering early.
+    virtual void MaybeRenderEarly(
+        const std::vector<int32_t>& pictures_out_for_display) {}
 
     // Notify strategy that we have a new android MediaCodec instance.  This
     // happens when we're starting up or re-configuring mid-stream.  Any
@@ -317,6 +323,10 @@ class CONTENT_EXPORT AndroidVideoDecodeAccelerator
   // decoded frames to the client.
   std::queue<int32_t> free_picture_ids_;
 
+  // Picture buffer IDs that are out for display. Stored in order of frames as
+  // they are returned from the decoder.
+  std::vector<int32_t> pictures_out_for_display_;
+
   // The low-level decoder which Android SDK provides.
   std::unique_ptr<media::VideoCodecBridge> media_codec_;