mus: Implement Window Server Capture

components/mus/view_tree_host_impl.h

Index: components/mus/view_tree_host_impl.h
diff --git a/components/mus/view_tree_host_impl.h b/components/mus/view_tree_host_impl.h
index 3aaeb808fe88f0808c0e586f4791ae6f2dd8b7eb..98ee797e14c13d33ebae67a550c7f40ab254cb26 100644
--- a/components/mus/view_tree_host_impl.h
+++ b/components/mus/view_tree_host_impl.h
@@ -73,6 +73,8 @@ class ViewTreeHostImpl : public DisplayManagerDelegate,
   ServerView* root_view() { return root_.get(); }
   const ServerView* root_view() const { return root_.get(); }
 
+  void SetCapture(ServerView* view);
+
   void SetFocusedView(ServerView* view);
   ServerView* GetFocusedView();
   void DestroyFocusController();
@@ -97,6 +99,7 @@ class ViewTreeHostImpl : public DisplayManagerDelegate,
   // DisplayManagerDelegate:
   ServerView* GetRootView() override;
   void OnEvent(mojo::EventPtr event) override;
+  void OnLostCapture() override;
   void OnDisplayClosed() override;
   void OnViewportMetricsChanged(
       const mojo::ViewportMetrics& old_metrics,
@@ -113,6 +116,7 @@ class ViewTreeHostImpl : public DisplayManagerDelegate,
   scoped_ptr<ServerView> root_;
   scoped_ptr<DisplayManager> display_manager_;
   scoped_ptr<FocusController> focus_controller_;
+  ServerView* captured_view_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewTreeHostImpl);
 };