Let ViEEncoder handle resolution changes.

webrtc/test/frame_generator_capturer.h

Index: webrtc/test/frame_generator_capturer.h
diff --git a/webrtc/test/frame_generator_capturer.h b/webrtc/test/frame_generator_capturer.h
index 2b2cfbc82133706b16aa67075823d32372731cd6..fa001c4edff071a3da446e3aaad95538ece842d2 100644
--- a/webrtc/test/frame_generator_capturer.h
+++ b/webrtc/test/frame_generator_capturer.h
@@ -45,6 +45,7 @@ class FrameGeneratorCapturer : public VideoCapturer {
 
   void Start() override;
   void Stop() override;
+  void ChangeResolution(size_t width, size_t height);
 
   void AddOrUpdateSink(rtc::VideoSinkInterface<VideoFrame>* sink,
                        const rtc::VideoSinkWants& wants) override;