Allow for framerate reduction for HW encoder.

R=pbos@webrtc.org, stefan@webrtc.org
TBR=glaznev@google.com

Review URL: https://webrtc-codereview.appspot.com/51159004 .

Cr-Commit-Position: refs/heads/master@{#9573}

webrtc/modules/video_coding/main/source/generic_encoder.cc

@@ -214,6 +214,10 @@ bool VCMGenericEncoder::SupportsNativeHandle() const {
   return encoder_->SupportsNativeHandle();
 }
 
+int VCMGenericEncoder::GetTargetFramerate() {
+  return encoder_->GetTargetFramerate();
+}
+
  /***************************
   * Callback Implementation
   ***************************/