Remove Observer methods in RTCVideoEncoderFactory.

These methods are no-ops in the current implementations and are going
away in the upstream interface, where a default implementation is
provided in the interrim.

R=tommi@chromium.org
BUG=webrtc:3876

Review URL: https://codereview.chromium.org/639393002

Cr-Commit-Position: refs/heads/master@{#299089}

content/renderer/media/rtc_video_encoder_factory.cc

@@ -87,12 +87,6 @@ webrtc::VideoEncoder* RTCVideoEncoderFactory::CreateVideoEncoder(
       type, WebRTCCodecToVideoCodecProfile(type), gpu_factories_);
 }
 
-void RTCVideoEncoderFactory::AddObserver(Observer* observer) {
-  // No-op: our codec list is populated on installation.
-}
-
-void RTCVideoEncoderFactory::RemoveObserver(Observer* observer) {}
-
 const std::vector<cricket::WebRtcVideoEncoderFactory::VideoCodec>&
 RTCVideoEncoderFactory::codecs() const {
   return codecs_;

content/renderer/media/rtc_video_encoder_factory.h

@@ -32,8 +32,6 @@ class CONTENT_EXPORT RTCVideoEncoderFactory
   // cricket::WebRtcVideoEncoderFactory implementation.
   virtual webrtc::VideoEncoder* CreateVideoEncoder(
       webrtc::VideoCodecType type) override;
-  virtual void AddObserver(Observer* observer) override;
-  virtual void RemoveObserver(Observer* observer) override;
   virtual const std::vector<VideoCodec>& codecs() const override;
   virtual void DestroyVideoEncoder(webrtc::VideoEncoder* encoder) override;