Remove hardcoded kValueSizeBytes values from variable-length header extensions.

webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc b/webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc
index 26762b0e9662a567c14d21e92e779b6247819b0a..25fe5445b4b0eed8514a746bd598ec02241b6366 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc
@@ -23,13 +23,12 @@ using RtpUtility::Word32Align;
 
 struct ExtensionInfo {
   RTPExtensionType type;
-  size_t value_size;
   const char* uri;
 };
 
 template <typename Extension>
 constexpr ExtensionInfo CreateExtensionInfo() {
-  return {Extension::kId, Extension::kValueSizeBytes, Extension::kUri};
+  return {Extension::kId, Extension::kUri};
 }
 
 constexpr ExtensionInfo kExtensions[] = {
@@ -50,15 +49,6 @@ static_assert(arraysize(kExtensions) ==
                   static_cast<int>(kRtpExtensionNumberOfExtensions) - 1,
               "kExtensions expect to list all known extensions");
 
-size_t ValueSize(RTPExtensionType type) {
-  for (const ExtensionInfo& extension : kExtensions)
-    if (type == extension.type)
-      return extension.value_size;
-
-  RTC_NOTREACHED();
-  return 0;
-}
-
 }  // namespace
 
 constexpr RTPExtensionType RtpHeaderExtensionMap::kInvalidType;
@@ -67,7 +57,6 @@ constexpr uint8_t RtpHeaderExtensionMap::kMinId;
 constexpr uint8_t RtpHeaderExtensionMap::kMaxId;
 
 RtpHeaderExtensionMap::RtpHeaderExtensionMap() {
-  total_values_size_bytes_ = 0;
   for (auto& type : types_)
     type = kInvalidType;
   for (auto& id : ids_)
@@ -84,7 +73,7 @@ RtpHeaderExtensionMap::RtpHeaderExtensionMap(
 bool RtpHeaderExtensionMap::RegisterByType(uint8_t id, RTPExtensionType type) {
   for (const ExtensionInfo& extension : kExtensions)
     if (type == extension.type)
-      return Register(id, extension.type, extension.value_size, extension.uri);
+      return Register(id, extension.type, extension.uri);
   RTC_NOTREACHED();
   return false;
 }
@@ -92,23 +81,29 @@ bool RtpHeaderExtensionMap::RegisterByType(uint8_t id, RTPExtensionType type) {
 bool RtpHeaderExtensionMap::RegisterByUri(uint8_t id, const std::string& uri) {
   for (const ExtensionInfo& extension : kExtensions)
     if (uri == extension.uri)
-      return Register(id, extension.type, extension.value_size, extension.uri);
+      return Register(id, extension.type, extension.uri);
   LOG(LS_WARNING) << "Unknown extension uri:'" << uri
                   << "', id: " << static_cast<int>(id) << '.';
   return false;
 }
 
-size_t RtpHeaderExtensionMap::GetTotalLengthInBytes() const {
+size_t RtpHeaderExtensionMap::GetTotalLengthInBytes(
+    rtc::ArrayView<const RtpExtensionSize> extensions) const {
   static constexpr size_t kRtpOneByteHeaderLength = 4;
-  if (total_values_size_bytes_ == 0)
+  static constexpr size_t kExtensionSizeOverhead = 1;

[danilchap, 2017/05/09 14:45:22]

may be kExtensionHeaderLength = 1
May be with so many headers involved add comment both for this one and for the
constant above:
// Header size of the extension block, See RFC3550 Section 5.3.1
// Header size of each individual extension. See RFC5285 Section 4.2

[erikvarga1, 2017/05/09 15:19:41]

Oh, right, that one byte is not only the size but also the ID. In that case
ExtensionHeader does make more sense. Done.

+  size_t value_size = 0;

[danilchap, 2017/05/09 14:45:22]

values_size (since it represent size of several values)

[erikvarga1, 2017/05/09 15:19:41]

Ah, I missed that 's' in the previous comment. Done now.

+  for (const RtpExtensionSize& extension : extensions) {
+    if (IsRegistered(extension.type))
+      value_size += extension.value_size + kExtensionSizeOverhead;
+  }
+  if (value_size == 0)
     return 0;
-  return Word32Align(kRtpOneByteHeaderLength + total_values_size_bytes_);
+  return Word32Align(kRtpOneByteHeaderLength + value_size);
 }
 
 int32_t RtpHeaderExtensionMap::Deregister(RTPExtensionType type) {
   if (IsRegistered(type)) {
     uint8_t id = GetId(type);
-    total_values_size_bytes_ -= (ValueSize(type) + 1);
     types_[id] = kInvalidType;
     ids_[type] = kInvalidId;
   }
@@ -117,12 +112,9 @@ int32_t RtpHeaderExtensionMap::Deregister(RTPExtensionType type) {
 
 bool RtpHeaderExtensionMap::Register(uint8_t id,
                                      RTPExtensionType type,
-                                     size_t value_size,
                                      const char* uri) {
   RTC_DCHECK_GT(type, kRtpExtensionNone);
   RTC_DCHECK_LT(type, kRtpExtensionNumberOfExtensions);
-  RTC_DCHECK_GE(value_size, 1U);
-  RTC_DCHECK_LE(value_size, 16U);
 
   if (id < kMinId || id > kMaxId) {
     LOG(LS_WARNING) << "Failed to register extension uri:'" << uri
@@ -147,7 +139,6 @@ bool RtpHeaderExtensionMap::Register(uint8_t id,
 
   types_[id] = type;
   ids_[type] = id;
-  total_values_size_bytes_ += (value_size + 1);
   return true;
 }