Add pps id and sps id parsing to the h.264 depacketizer.

webrtc/common_video/h264/pps_parser.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 15 matching lines @@
   // The parsed state of the PPS. Only some select values are stored.
   // Add more as they are actually needed.
   struct PpsState {
     PpsState() = default;
 
     bool bottom_field_pic_order_in_frame_present_flag = false;
     bool weighted_pred_flag = false;
     uint32_t weighted_bipred_idc = false;
     uint32_t redundant_pic_cnt_present_flag = 0;
     int pic_init_qp_minus26 = 0;
+    uint32_t id = 0;
+    uint32_t sps_id = 0;
   };
 
   // Unpack RBSP and parse PPS state from the supplied buffer.
   static rtc::Optional<PpsState> ParsePps(const uint8_t* data, size_t length);
 
+  static rtc::Optional<uint32_t> ParsePpsIdFromSlice(const uint8_t* data,
+                                                     size_t length);
+
  protected:
   // Parse the PPS state, for a bit buffer where RBSP decoding has already been
   // performed.
   static rtc::Optional<PpsState> ParseInternal(rtc::BitBuffer* bit_buffer);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_VIDEO_H264_PPS_PARSER_H_