Return a copy of the supported RTP header extensions instead of a reference.

talk/media/base/fakemediaengine.h

Index: talk/media/base/fakemediaengine.h
diff --git a/talk/media/base/fakemediaengine.h b/talk/media/base/fakemediaengine.h
index 6c97b4a8ab474690bd83dd70b1a618d7a34c6560..f0743ef2f49d7b75719518ed966976861fe7430a 100644
--- a/talk/media/base/fakemediaengine.h
+++ b/talk/media/base/fakemediaengine.h
@@ -698,7 +698,7 @@ class FakeBaseEngine {
         fail_create_channel_(false) {}
   void set_fail_create_channel(bool fail) { fail_create_channel_ = fail; }
 
-  const std::vector<RtpHeaderExtension>& rtp_header_extensions() const {
+  std::vector<RtpHeaderExtension> SupportedRtpHeaderExtensions() const {

[pthatcher1, 2015/12/01 18:40:46]

Can we please just skip right to what we want this to be called eventually?

RtpCapabilities GetCapabilities();

struct RtpCapabilities {
  std::vector<RtpHeaderExtension> header_extensions;
};

[stefan-webrtc, 2015/12/04 14:06:10]

Done.

     return rtp_header_extensions_;
   }
   void set_rtp_header_extensions(