Don't treat picture ids as wrapping in the FrameBuffer2 class.

webrtc/modules/video_coding/frame_buffer2.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 58 matching lines @@
   // Start the frame buffer, has no effect if the frame buffer is started.
   // The frame buffer is started upon construction.
   void Start();
 
   // Stop the frame buffer, causing any sleeping thread in NextFrame to
   // return immediately.
   void Stop();
 
  private:
   struct FrameKey {
-    FrameKey() : picture_id(0), spatial_layer(0) {}
-    FrameKey(uint16_t picture_id, uint8_t spatial_layer)
+    FrameKey() : picture_id(-1), spatial_layer(0) {}
+    FrameKey(int64_t picture_id, uint8_t spatial_layer)
         : picture_id(picture_id), spatial_layer(spatial_layer) {}
 
     bool operator<(const FrameKey& rhs) const {
       if (picture_id == rhs.picture_id)
         return spatial_layer < rhs.spatial_layer;
-      return AheadOf(rhs.picture_id, picture_id);
+      return picture_id < rhs.picture_id;
     }
 
     bool operator<=(const FrameKey& rhs) const { return !(rhs < *this); }
 
-    uint16_t picture_id;
+    int64_t picture_id;
     uint8_t spatial_layer;
   };
 
   struct FrameInfo {
     // The maximum number of frames that can depend on this frame.
     static constexpr size_t kMaxNumDependentFrames = 8;
 
     // Which other frames that have direct unfulfilled dependencies
     // on this frame.
     // TODO(philipel): Add simple modify/access functions to prevent adding too
@@ skipping 78 matching lines @@
   VCMReceiveStatisticsCallback* const stats_callback_;
   int64_t last_log_non_decoded_ms_ RTC_GUARDED_BY(crit_);
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(FrameBuffer);
 };
 
 }  // namespace video_coding
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_FRAME_BUFFER2_H_