Revert of Rename RTPVideoHeader.isFirstPacket to .is_first_packet_in_frame.

webrtc/modules/video_coding/packet.h

 /*
  *  Copyright (c) 2011 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 21 matching lines @@
   int64_t ntp_time_ms_;
   uint16_t seqNum;
   const uint8_t* dataPtr;
   size_t sizeBytes;
   bool markerBit;
   int timesNacked;
 
   FrameType frameType;
   VideoCodecType codec;
 
-  bool is_first_packet_in_frame;     // Is this first packet in a frame.
+  bool isFirstPacket;                // Is this first packet in a frame.
   VCMNaluCompleteness completeNALU;  // Default is kNaluIncomplete.
   bool insertStartCode;  // True if a start code should be inserted before this
                          // packet.
   int width;
   int height;
   RTPVideoHeader video_header;
 
  protected:
   void CopyCodecSpecifics(const RTPVideoHeader& videoHeader);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_VIDEO_CODING_PACKET_H_