Removing `preference` field from `cricket::Codec`.

webrtc/pc/mediasession.h

Index: webrtc/pc/mediasession.h
diff --git a/webrtc/pc/mediasession.h b/webrtc/pc/mediasession.h
index ae221554e20b596a569db934fdb285b37183614d..98a1f070d687ec8457f3f22a8be70899d8ee5517 100644
--- a/webrtc/pc/mediasession.h
+++ b/webrtc/pc/mediasession.h
@@ -293,10 +293,9 @@ class MediaContentDescription : public ContentDescription {
 template <class C>
 class MediaContentDescriptionImpl : public MediaContentDescription {
  public:
-  struct PreferenceSort {
-    bool operator()(C a, C b) { return a.preference > b.preference; }
-  };
+  typedef C CodecType;
 
+  // Codecs should be in preference order (most preferred codec first).
   const std::vector<C>& codecs() const { return codecs_; }
   void set_codecs(const std::vector<C>& codecs) { codecs_ = codecs; }
   virtual bool has_codecs() const { return !codecs_.empty(); }
@@ -330,9 +329,6 @@ class MediaContentDescriptionImpl : public MediaContentDescription {
       AddCodec(*codec);
     }
   }
-  void SortCodecs() {
-    std::sort(codecs_.begin(), codecs_.end(), PreferenceSort());
-  }
 
  private:
   std::vector<C> codecs_;