Add a ParseHeader method to RtcpPacket, for parsing common RTCP header.

webrtc/modules/rtp_rtcp/source/rtcp_utility.h

Index: webrtc/modules/rtp_rtcp/source/rtcp_utility.h
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_utility.h b/webrtc/modules/rtp_rtcp/source/rtcp_utility.h
index fcafe5960ee883fa04c4d17164fd1ed89b43ea81..f95cc29cf09553fca4b409516759c5ebcb363f03 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_utility.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_utility.h
@@ -306,12 +306,24 @@ struct RTCPModRawPacket {
   uint8_t* _ptrPacketEnd;
 };
 
-struct RTCPCommonHeader {
-  uint8_t V;   // Version
-  bool P;      // Padding
-  uint8_t IC;  // Item count/subtype
-  uint8_t PT;  // Packet Type
-  uint16_t LengthInOctets;
+struct RtcpCommonHeader {
+  static const uint8_t kHeaderSizeBytes = 4;
+  RtcpCommonHeader()
+      : version(2),
+        count_or_format(0),
+        packet_type(0),
+        payload_size_bytes(0),
+        padding_bytes(0) {}
+
+  uint32_t BlockSize() const {
+    return kHeaderSizeBytes + payload_size_bytes + padding_bytes;
+  }
+
+  uint8_t version;
+  uint8_t count_or_format;
+  uint8_t packet_type;
+  uint32_t payload_size_bytes;
+  uint8_t padding_bytes;
 };
 
 enum RTCPPT : uint8_t {
@@ -333,9 +345,10 @@ enum RtcpXrBlockType : uint8_t {
   kBtVoipMetric = 7
 };
 
-bool RTCPParseCommonHeader(const uint8_t* ptrDataBegin,
-                           const uint8_t* ptrDataEnd,
-                           RTCPCommonHeader& parsedHeader);
+bool RtcpParseCommonHeader(const uint8_t* buffer,
+                           size_t index,
+                           size_t max_length,
+                           RtcpCommonHeader* parsed_header);
 
 class RTCPParserV2 {
  public:
@@ -418,7 +431,7 @@ class RTCPParserV2 {
   bool ParseXrVoipMetricItem(int block_length_4bytes);
   bool ParseXrUnsupportedBlockType(int block_length_4bytes);
 
-  bool ParseFBCommon(const RTCPCommonHeader& header);
+  bool ParseFBCommon(const RtcpCommonHeader& header);
   bool ParseNACKItem();
   bool ParseTMMBRItem();
   bool ParseTMMBNItem();
@@ -428,7 +441,7 @@ class RTCPParserV2 {
   bool ParsePsfbAppItem();
   bool ParsePsfbREMBItem();
 
-  bool ParseAPP(const RTCPCommonHeader& header);
+  bool ParseAPP(const RtcpCommonHeader& header);
   bool ParseAPPItem();
 
  private:
@@ -452,9 +465,9 @@ class RTCPPacketIterator {
   RTCPPacketIterator(uint8_t* rtcpData, size_t rtcpDataLength);
   ~RTCPPacketIterator();
 
-  const RTCPCommonHeader* Begin();
-  const RTCPCommonHeader* Iterate();
-  const RTCPCommonHeader* Current();
+  const RtcpCommonHeader* Begin();
+  const RtcpCommonHeader* Iterate();
+  const RtcpCommonHeader* Current();
 
  private:
   uint8_t* const _ptrBegin;
@@ -462,7 +475,7 @@ class RTCPPacketIterator {
 
   uint8_t* _ptrBlock;
 
-  RTCPCommonHeader _header;
+  RtcpCommonHeader _header;
 };
 }  // RTCPUtility
 }  // namespace webrtc