FrameBuffer::NextFrame now return pair<frame, reason>.

webrtc/modules/video_coding/frame_buffer2.h

Index: webrtc/modules/video_coding/frame_buffer2.h
diff --git a/webrtc/modules/video_coding/frame_buffer2.h b/webrtc/modules/video_coding/frame_buffer2.h
index 0af2bf952350bc76674f5f42dcbf8f86fff8e80e..3adb36af91a9db81257a4164c2bec535ffc14a43 100644
--- a/webrtc/modules/video_coding/frame_buffer2.h
+++ b/webrtc/modules/video_coding/frame_buffer2.h
@@ -36,6 +36,12 @@ class FrameObject;
 
 class FrameBuffer {
  public:
+  enum ReturnReason {
+    kFrameFound,
+    kTimeout,
+    kStopped
+  };
+
   FrameBuffer(Clock* clock,
               VCMJitterEstimator* jitter_estimator,
               VCMTiming* timing);
@@ -44,9 +50,15 @@ class FrameBuffer {
   void InsertFrame(std::unique_ptr<FrameObject> frame);
 
   // Get the next frame for decoding. Will return at latest after
-  // |max_wait_time_ms|, with either a managed FrameObject or an empty
-  // unique ptr if there is no available frame for decoding.
-  std::unique_ptr<FrameObject> NextFrame(int64_t max_wait_time_ms);
+  // |max_wait_time_ms|.
+  //  - If a frame is availiable within |max_wait_time_ms| it will return
+  //    {non-null unique ptr, kFrameFound}
+  //  - If no frame is available after |max_wait_time_ms| it will return
+  //    {null unique ptr, kTimeout}
+  //  - If the FrameBuffer is stopped then it will return
+  //    {null unique ptr, kStopped}
+  std::pair<std::unique_ptr<FrameObject>, ReturnReason>

[mflodman, 2016/09/02 12:05:57]

I'm not a big fan of returning a pair like this, wdyt of instead moving
FrameObject to the argument list?

[philipel, 2016/09/02 12:41:31]

The idea was to follow the stl style where pair<object, status> often is
returned, changed now to take an additional output parameter.

+      NextFrame(int64_t max_wait_time_ms);
 
   // Tells the FrameBuffer which protection mode that is in use. Affects
   // the frame timing.