mus: Implement Window Server Capture

components/mus/display_manager.cc

Index: components/mus/display_manager.cc
diff --git a/components/mus/display_manager.cc b/components/mus/display_manager.cc
index 195d5a138e3f83ccfd862abccdfe004256e96109..d13c406aeb88b75d972722b2d238362c63832338 100644
--- a/components/mus/display_manager.cc
+++ b/components/mus/display_manager.cc
@@ -171,6 +171,10 @@ void DefaultDisplayManager::SetTitle(const base::string16& title) {
   platform_window_->SetTitle(title);
 }
 
+void DefaultDisplayManager::SetCapture() {
+  platform_window_->SetCapture();
+}
+
 const mojo::ViewportMetrics& DefaultDisplayManager::GetViewportMetrics() {
   return metrics_;
 }
@@ -315,7 +319,9 @@ void DefaultDisplayManager::OnClosed() {
 void DefaultDisplayManager::OnWindowStateChanged(
     ui::PlatformWindowState new_state) {}
 
-void DefaultDisplayManager::OnLostCapture() {}
+void DefaultDisplayManager::OnLostCapture() {
+  delegate_->OnLostCapture();
+}
 
 void DefaultDisplayManager::OnAcceleratedWidgetAvailable(
     gfx::AcceleratedWidget widget,