ui: Cleanup class/struct forward declarations

remoting/host/single_window_desktop_environment.cc

Index: remoting/host/single_window_desktop_environment.cc
diff --git a/remoting/host/single_window_desktop_environment.cc b/remoting/host/single_window_desktop_environment.cc
index 8456542e1a5d2ab82ad804234a864b476c90ca07..d638751efc911eb04853d194a9f738957cfa1432 100644
--- a/remoting/host/single_window_desktop_environment.cc
+++ b/remoting/host/single_window_desktop_environment.cc
@@ -33,10 +33,10 @@ class SingleWindowDesktopEnvironment : public BasicDesktopEnvironment {
       scoped_refptr<base::SingleThreadTaskRunner> video_capture_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> input_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
-      webrtc::WindowId window_id);
+      webrtc::DesktopCapturer::SourceId window_id);
 
  private:
-  webrtc::WindowId window_id_;
+  webrtc::DesktopCapturer::SourceId window_id_;
 
   DISALLOW_COPY_AND_ASSIGN(SingleWindowDesktopEnvironment);
 };
@@ -51,11 +51,11 @@ SingleWindowDesktopEnvironment::CreateVideoCapturer() {
       webrtc::DesktopCaptureOptions::CreateDefault();
   options.set_use_update_notifications(true);
 
-  std::unique_ptr<webrtc::WindowCapturer> window_capturer(
-      webrtc::WindowCapturer::Create(options));
-  window_capturer->SelectWindow(window_id_);
+  std::unique_ptr<webrtc::DesktopCapturer> window_capturer(
+      webrtc::DesktopCapturer::CreateWindowCapturer(options));
+  window_capturer->SelectSource(window_id_);
 
-  return std::move(window_capturer);
+  return window_capturer;
 }
 
 std::unique_ptr<InputInjector>