Don't write spaces after semicolons in FMTP lines.

webrtc/api/webrtcsdp.cc

 /*
  *  Copyright 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 1546 matching lines @@
                         const std::string& parameter_value,
                         std::ostringstream* os) {
   // fmtp parameters: |parameter_name|=|parameter_value|
   *os << parameter_name << kSdpDelimiterEqual << parameter_value;
 }
 
 void WriteFmtpParameters(const cricket::CodecParameterMap& parameters,
                          std::ostringstream* os) {
   for (cricket::CodecParameterMap::const_iterator fmtp = parameters.begin();
        fmtp != parameters.end(); ++fmtp) {
-    // Each new parameter, except the first one starts with ";" and " ".
-    if (fmtp != parameters.begin()) {
+    // Parameters are a semicolon-separated list, no spaces.
+    // The list is separated from the header by a space.
+    if (fmtp == parameters.begin()) {
+      *os << kSdpDelimiterSpace;
+    } else {
       *os << kSdpDelimiterSemicolon;
     }
-    *os << kSdpDelimiterSpace;
     WriteFmtpParameter(fmtp->first, fmtp->second, os);
   }
 }
 
 bool IsFmtpParam(const std::string& name) {
   const char* kFmtpParams[] = {
       // TODO(hta): Split FMTP parameters apart from parameters in general.
       // FMTP parameters are codec specific, not generic.
       kCodecParamMinPTime,
       kCodecParamSPropStereo,
@@ skipping 1589 matching lines @@
     UpdateCodec<AudioContentDescription, cricket::AudioCodec>(
         media_desc, payload_type, feedback_param);
   } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
     UpdateCodec<VideoContentDescription, cricket::VideoCodec>(
         media_desc, payload_type, feedback_param);
   }
   return true;
 }
 
 }  // namespace webrtc