[remoting host] Remove VideoControl lossless-color implementation.

This CL prevents WebRTC clients from changing the VP9 lossless-color
property via a VideoControl message. This is because WebRTC handles
that setting via the SDP codec parameter "profile-id=1", which means
an SDP offer/answer exchange is needed to properly control this
setting. Non-WebRTC clients are not affected and they can still toggle
lossless-color via a VideoControl message.

This CL also adds logging to the VP9 encoder so we can verify what
settings are being applied at the codec level.

This also fixes a bug where the SDP parameter for lossless-color was
not being respected.

Bug: 1113499
Change-Id: I15ca83b0fcc157a3b63d3a3ca3509039ed47b24f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342126
Auto-Submit: Lambros Lambrou <lambroslambrou@chromium.org>
Commit-Queue: Jamie Walch <jamiewalch@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795973}

remoting/codec/webrtc_video_encoder_vpx.cc

@@ -416,6 +416,13 @@ void WebrtcVideoEncoderVpx::Configure(const webrtc::DesktopSize& size) {
   DCHECK(use_vp9_ || !lossless_color_);
   DCHECK(use_vp9_ || !lossless_encode_);
 
+  if (use_vp9_) {
+    VLOG(0) << "Configuring VP9 encoder with lossless-color="
+            << (lossless_color_ ? "true" : "false")
+            << ", lossless-encode=" << (lossless_encode_ ? "true" : "false")
+            << ".";
+  }
+
   // Tear down |image_| if it no longer matches the size and color settings.
   // PrepareImage() will then create a new buffer of the required dimensions if
   // |image_| is not allocated.

remoting/protocol/webrtc_video_stream.cc

@@ -190,10 +190,8 @@ void WebrtcVideoStream::SetLosslessEncode(bool want_lossless) {
 }
 
 void WebrtcVideoStream::SetLosslessColor(bool want_lossless) {
-  lossless_color_ = want_lossless;
-  if (encoder_) {
-    encoder_->SetLosslessColor(want_lossless);
-  }
+  NOTIMPLEMENTED() << "Changing lossless-color for VP9 requires SDP "
+                      "offer/answer exchange.";
 }
 
 void WebrtcVideoStream::SetObserver(Observer* observer) {
@@ -233,7 +231,6 @@ void WebrtcVideoStream::OnCaptureResult(
     encoder_selector_.SetDesktopFrame(*frame);
     encoder_ = encoder_selector_.CreateEncoder();
     encoder_->SetLosslessEncode(lossless_encode_);
-    encoder_->SetLosslessColor(lossless_color_);
 
     // TODO(zijiehe): Permanently stop the video stream if we cannot create an
     // encoder for the |frame|.

remoting/protocol/webrtc_video_stream.h

@@ -113,8 +113,11 @@ class WebrtcVideoStream : public VideoStream,
 
   // Settings that are received from video-control messages. These are stored
   // here in case a message is received before the encoder is created.
+  // Lossless-color is not stored here because, for VP9 encoder, WebRTC handles
+  // it via an SDP codec parameter, "profile-id=1". Changing it requires a
+  // new SDP offer/answer exchange, and therefore it cannot be changed directly
+  // via video-control message.
   bool lossless_encode_ = false;
-  bool lossless_color_ = false;
 
   base::WeakPtrFactory<WebrtcVideoStream> weak_factory_{this};