Rework PerformanceTracker to make it usable with WebRTC

remoting/client/plugin/pepper_video_renderer_3d.h

Index: remoting/client/plugin/pepper_video_renderer_3d.h
diff --git a/remoting/client/plugin/pepper_video_renderer_3d.h b/remoting/client/plugin/pepper_video_renderer_3d.h
index e2471ff889e9d59aeaa9798731e4e8a8bf355d38..04fb123cbf5ba6687039e2d3e3c2e4f959251e67 100644
--- a/remoting/client/plugin/pepper_video_renderer_3d.h
+++ b/remoting/client/plugin/pepper_video_renderer_3d.h
@@ -7,7 +7,7 @@
 
 #include <stdint.h>
 
-#include <deque>
+#include <list>
 #include <memory>
 #include <string>
 
@@ -51,13 +51,15 @@ class PepperVideoRenderer3D : public PepperVideoRenderer,
                           const base::Closure& done) override;
 
  private:
-  class PendingPacket;
+  // Class responsible for tracking state of a frame until it's rendered.
+  class FrameTracker;
+
   class Picture;
 
   // Callback for pp::VideoDecoder::Initialize().
   void OnInitialized(int32_t result);
 
-  // Passes one picture from |pending_packets_| to the |video_decoder_|.
+  // Passes one picture from |pending_frames_| to the |video_decoder_|.
   void DecodeNextPacket();
 
   // Callback for pp::VideoDecoder::Decode().
@@ -105,19 +107,29 @@ class PepperVideoRenderer3D : public PepperVideoRenderer,
   bool get_picture_pending_ = false;
   bool paint_pending_ = false;
 
-  // Queue of packets that that have been received, but haven't been passed to
-  // the decoder yet.
-  std::deque<PendingPacket*> pending_packets_;
+  // Frames that have been received, but haven't been passed to the decoder yet.
+  std::list<std::unique_ptr<FrameTracker>> pending_frames_;
 
-  // The current picture shown on the screen or being rendered. Must be deleted
-  // before |video_decoder_|.
-  std::unique_ptr<Picture> current_picture_;
+  // Frames that have been decoded but for which we haven't received the
+  // pictures yet.
+  std::list<std::unique_ptr<FrameTracker>> decoded_frames_;
 
   // The next picture to be rendered. PaintIfNeeded() will copy it to
   // |current_picture_| and render it after that. Must be deleted
   // before |video_decoder_|.
   std::unique_ptr<Picture> next_picture_;
 
+  // FrameTracker instances in |next_picture_|.
+  std::list<std::unique_ptr<FrameTracker>> next_picture_frames_;
+
+  // The current picture shown on the screen or being rendered. Must be deleted
+  // before |video_decoder_|.
+  std::unique_ptr<Picture> current_picture_;
+
+  // FrameTrackers for frames in |current_picture_|. The queue is emptied once
+  // the |current_picture_| is rendered.
+  std::list<std::unique_ptr<FrameTracker>> current_picture_frames_;
+
   // Set to true if the screen has been resized and needs to be repainted.
   bool force_repaint_ = false;