Add helper function for SPDY 4

This lands server change 44568667.

Review URL: https://codereview.chromium.org/13598037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@192885 0039d316-1c4b-4281-b951-d872f2087c98

net/spdy/spdy_framer.cc

@@ -253,6 +253,13 @@ size_t SpdyFramer::GetCredentialMinimumSize() const {
   return GetControlFrameHeaderSize() + 2;
 }
 
+size_t SpdyFramer::GetDataFrameMaximumPayload() const {
+  if (protocol_version() < 4) {
+    return 0xffffff - GetDataFrameMinimumSize();
+  }
+  return 0xffff - GetDataFrameMinimumSize();
+}
+
 const char* SpdyFramer::StateToString(int state) {
   switch (state) {
     case SPDY_ERROR:

net/spdy/spdy_framer.h

@@ -488,6 +488,9 @@ class NET_EXPORT_PRIVATE SpdyFramer {
   size_t GetWindowUpdateSize() const;
   size_t GetCredentialMinimumSize() const;
 
+  // Returns the maximum payload size of a DATA frame.
+  size_t GetDataFrameMaximumPayload() const;
+
   // For debugging.
   static const char* StateToString(int state);
   static const char* ErrorCodeToString(int error_code);