Fix WebrtcVideoStream to handle failed capture requests.

remoting/host/desktop_session_proxy.cc

Index: remoting/host/desktop_session_proxy.cc
diff --git a/remoting/host/desktop_session_proxy.cc b/remoting/host/desktop_session_proxy.cc
index 84b6a0638da764f018979403e740ba92f823f6c7..4e9e88b97c8a503fe0aa256c65c277e84cce724c 100644
--- a/remoting/host/desktop_session_proxy.cc
+++ b/remoting/host/desktop_session_proxy.cc
@@ -248,7 +248,7 @@ void DesktopSessionProxy::DetachFromDesktop() {
   while (pending_capture_frame_requests_) {
     --pending_capture_frame_requests_;
     video_capturer_->OnCaptureResult(
-        webrtc::DesktopCapturer::Result::ERROR_PERMANENT, nullptr);
+        webrtc::DesktopCapturer::Result::ERROR_TEMPORARY, nullptr);
   }
 }
 
@@ -267,7 +267,7 @@ void DesktopSessionProxy::CaptureFrame() {
     SendToDesktop(new ChromotingNetworkDesktopMsg_CaptureFrame());
   } else {
     video_capturer_->OnCaptureResult(
-        webrtc::DesktopCapturer::Result::ERROR_PERMANENT, nullptr);
+        webrtc::DesktopCapturer::Result::ERROR_TEMPORARY, nullptr);
   }
 }