Add histogram for percentage of incoming frames that are limited in resolution due to cpu

webrtc/media/engine/webrtcvideoengine2.h

Index: webrtc/media/engine/webrtcvideoengine2.h
diff --git a/webrtc/media/engine/webrtcvideoengine2.h b/webrtc/media/engine/webrtcvideoengine2.h
index 9413047cb305ddf440b68a62731d47270ed7a9f2..55da67adcde5e580522ea3b5f518ebb321535bad 100644
--- a/webrtc/media/engine/webrtcvideoengine2.h
+++ b/webrtc/media/engine/webrtcvideoengine2.h
@@ -364,6 +364,8 @@ class WebRtcVideoChannel2 : public VideoMediaChannel, public webrtc::Transport {
     // and whether or not the encoding in |rtp_parameters_| is active.
     void UpdateSendState() EXCLUSIVE_LOCKS_REQUIRED(lock_);
 
+    void UpdateHistograms() const EXCLUSIVE_LOCKS_REQUIRED(lock_);
+
     rtc::ThreadChecker thread_checker_;
     rtc::AsyncInvoker invoker_;
     rtc::Thread* worker_thread_;
@@ -377,6 +379,10 @@ class WebRtcVideoChannel2 : public VideoMediaChannel, public webrtc::Transport {
     // Total number of times resolution as been requested to be changed due to
     // CPU adaptation.
     int number_of_cpu_adapt_changes_;
+    // Total number of frames sent to |stream_|.
+    int frame_count_ GUARDED_BY(lock_);
+    // Total number of cpu restricted frames sent to |stream_|.
+    int cpu_restricted_frame_count_ GUARDED_BY(lock_);
     rtc::VideoSourceInterface<cricket::VideoFrame>* source_;
     WebRtcVideoEncoderFactory* const external_encoder_factory_
         GUARDED_BY(lock_);