Delete unused method webrtc::VideoRendererInterface::SetSize.

BUG=webrtc:5426

Review URL: https://codereview.webrtc.org/1582493002

Cr-Commit-Position: refs/heads/master@{#11223}
diff --git a/talk/app/webrtc/mediastreaminterface.h b/talk/app/webrtc/mediastreaminterface.h
index a1c0c80..89a4abe 100644
--- a/talk/app/webrtc/mediastreaminterface.h
+++ b/talk/app/webrtc/mediastreaminterface.h
@@ -118,13 +118,6 @@
 // Interface for rendering VideoFrames from a VideoTrack
 class VideoRendererInterface {
  public:
-  // TODO(guoweis): Remove this function.  Obsolete. The implementation of
-  // VideoRendererInterface should be able to handle different frame size as
-  // well as pending rotation. If it can't apply the frame rotation by itself,
-  // it should call |frame|.GetCopyWithRotationApplied() to get a frame that has
-  // the rotation applied.
-  virtual void SetSize(int width, int height) {}
-
   // |frame| may have pending rotation. For clients which can't apply rotation,
   // |frame|->GetCopyWithRotationApplied() will return a frame that has the
   // rotation applied.