Fix off-by-one bugs in video_coding::PacketBuffer when the buffer is filled with a single frame.

webrtc/modules/video_coding/frame_object.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 24 matching lines @@
   virtual int64_t ReceivedTime() const = 0;
 
   // When this frame should be rendered.
   virtual int64_t RenderTime() const = 0;
 
   // This information is currently needed by the timing calculation class.
   // TODO(philipel): Remove this function when a new timing class has
   //                 been implemented.
   virtual bool delayed_by_retransmission() const { return 0; }
 
-  size_t size() { return _length; }
+  size_t size() const { return _length; }
 
   // The tuple (|picture_id|, |spatial_layer|) uniquely identifies a frame
   // object. For codec types that don't necessarily have picture ids they
   // have to be constructed from the header data relevant to that codec.
   uint16_t picture_id;
   uint8_t spatial_layer;
   uint32_t timestamp;
 
   // TODO(philipel): Add simple modify/access functions to prevent adding too
   // many |references|.
@@ skipping 37 matching lines @@
 
   // Equal to times nacked of the packet with the highet times nacked
   // belonging to this frame.
   int times_nacked_;
 };
 
 }  // namespace video_coding
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_FRAME_OBJECT_H_