Android media: VideoFrame should not store so many sync points.

media/base/video_frame.h

Index: media/base/video_frame.h
diff --git a/media/base/video_frame.h b/media/base/video_frame.h
index 8a607e02cd37e0baeecb459e87ae84ed61bf340d..0da4c3291652262e0df2a63d8b33af104758bac3 100644
--- a/media/base/video_frame.h
+++ b/media/base/video_frame.h
@@ -5,8 +5,6 @@
 #ifndef MEDIA_BASE_VIDEO_FRAME_H_
 #define MEDIA_BASE_VIDEO_FRAME_H_
 
-#include <vector>
-
 #include "base/callback.h"
 #include "base/md5.h"
 #include "base/memory/shared_memory.h"
@@ -86,7 +84,7 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
 
   // CB to be called on the mailbox backing this frame when the frame is
   // destroyed.
-  typedef base::Callback<void(const std::vector<uint32>&)> ReleaseMailboxCB;
+  typedef base::Callback<void(uint32)> ReleaseMailboxCB;
 
   // Wraps a native texture of the given parameters with a VideoFrame.  The
   // backing of the VideoFrame is held in the mailbox held by |mailbox_holder|,
@@ -256,12 +254,24 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
     timestamp_ = timestamp;
   }
 
-  // Append |sync_point| into |release_sync_points_| which will be passed to
+  class SyncPointClient {
+   public:
+    SyncPointClient() {}
+    virtual uint32 InsertSyncPoint() = 0;
+    virtual void WaitSyncPoint(uint32 sync_point) = 0;
+
+   protected:
+    virtual ~SyncPointClient() {}
+
+    DISALLOW_COPY_AND_ASSIGN(SyncPointClient);
+  };
+  // Set a new sync point to |release_sync_point_| which will be passed to

[no sievers, 2014/07/10 18:52:29]

nit: don't use internals like the private member |release_sync_point_| to
describe what's going on. how about some brief comment along the lines of saying
that "it uses |client| to insert a new sync point and potentially waits on older
sync points"?

   // the video decoder when |mailbox_holder_release_cb_| is called so that
-  // the video decoder waits for the sync points before reusing the mailbox.
-  // Multiple clients can append multiple sync points on one frame.
+  // the video decoder waits for the sync point before reusing the mailbox.
+  // A client should provide a SyncPointClient implementation to insert or
+  // wait a sync point.
   // This method is thread safe. Both blink and compositor threads can call it.
-  void AppendReleaseSyncPoint(uint32 sync_point);
+  void UpdateReleaseSyncPoint(SyncPointClient* client);
 
   // Used to keep a running hash of seen frames.  Expects an initialized MD5
   // context.  Calls MD5Update with the context and the contents of the frame.
@@ -330,7 +340,7 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
   base::TimeDelta timestamp_;
 
   base::Lock release_sync_point_lock_;
-  std::vector<uint32> release_sync_points_;
+  uint32 release_sync_point_;
 
   const bool end_of_stream_;