Add framerate to VideoSinkWants and ability to signal on overuse

webrtc/media/engine/webrtcvideoengine2.cc

Index: webrtc/media/engine/webrtcvideoengine2.cc
diff --git a/webrtc/media/engine/webrtcvideoengine2.cc b/webrtc/media/engine/webrtcvideoengine2.cc
index 8b4c5df1814601757b5d74b80eccf9087c745be5..e255a2cd62f0cdaf3a3bb7ae39fc0079d076e4a1 100644
--- a/webrtc/media/engine/webrtcvideoengine2.cc
+++ b/webrtc/media/engine/webrtcvideoengine2.cc
@@ -38,9 +38,10 @@
 #include "webrtc/video_decoder.h"
 #include "webrtc/video_encoder.h"
 
+using DegradationPreference = webrtc::VideoSendStream::DegradationPreference;
+
 namespace cricket {
 namespace {
-
 // If this field trial is enabled, we will enable sending FlexFEC and disable
 // sending ULPFEC whenever the former has been negotiated. Receiving FlexFEC
 // is enabled whenever FlexFEC has been negotiated.
@@ -1626,26 +1627,35 @@ bool WebRtcVideoChannel2::WebRtcVideoSendStream::SetVideoSend(
   }
 
   if (source_ && stream_) {
-    stream_->SetSource(
-        nullptr, webrtc::VideoSendStream::DegradationPreference::kBalanced);
+    stream_->SetSource(nullptr, DegradationPreference::kDegradationDisabled);
   }
   // Switch to the new source.
   source_ = source;
   if (source && stream_) {
-    // Do not adapt resolution for screen content as this will likely
-    // result in blurry and unreadable text.
-    // |this| acts like a VideoSource to make sure SinkWants are handled on the
-    // correct thread.
-    stream_->SetSource(
-        this, enable_cpu_overuse_detection_ &&
-                      !parameters_.options.is_screencast.value_or(false)
-                  ? webrtc::VideoSendStream::DegradationPreference::kBalanced
-                  : webrtc::VideoSendStream::DegradationPreference::
-                        kMaintainResolution);
+    stream_->SetSource(this, GetDegradationPreference());
   }
   return true;
 }
 
+webrtc::VideoSendStream::DegradationPreference
+WebRtcVideoChannel2::WebRtcVideoSendStream::GetDegradationPreference() const {
+  // Do not adapt resolution for screen content as this will likely
+  // result in blurry and unreadable text.
+  // |this| acts like a VideoSource to make sure SinkWants are handled on the
+  // correct thread.
+  DegradationPreference degradation_preference;
+  if (!enable_cpu_overuse_detection_) {
+    degradation_preference = DegradationPreference::kDegradationDisabled;
+  } else {
+    if (parameters_.options.is_screencast.value_or(false)) {
+      degradation_preference = DegradationPreference::kMaintainResolution;
+    } else {
+      degradation_preference = DegradationPreference::kMaintainFramerate;
+    }
+  }
+  return degradation_preference;
+}
+
 const std::vector<uint32_t>&
 WebRtcVideoChannel2::WebRtcVideoSendStream::GetSsrcs() const {
   return ssrcs_;
@@ -2083,16 +2093,7 @@ void WebRtcVideoChannel2::WebRtcVideoSendStream::RecreateWebRtcStream() {
   parameters_.encoder_config.encoder_specific_settings = NULL;
 
   if (source_) {
-    // Do not adapt resolution for screen content as this will likely result in
-    // blurry and unreadable text.
-    // |this| acts like a VideoSource to make sure SinkWants are handled on the
-    // correct thread.
-    stream_->SetSource(
-        this, enable_cpu_overuse_detection_ &&
-                      !parameters_.options.is_screencast.value_or(false)
-                  ? webrtc::VideoSendStream::DegradationPreference::kBalanced
-                  : webrtc::VideoSendStream::DegradationPreference::
-                        kMaintainResolution);
+    stream_->SetSource(this, GetDegradationPreference());
   }
 
   // Call stream_->Start() if necessary conditions are met.