mus Window Server: implement event capture

components/mus/ws/window_tree_host_impl.cc

Index: components/mus/ws/window_tree_host_impl.cc
diff --git a/components/mus/ws/window_tree_host_impl.cc b/components/mus/ws/window_tree_host_impl.cc
index d75b184a806be277716d0b7fc5c9ce2d45450b3b..293ba42a123a75db98441df8105fd60e616b9e69 100644
--- a/components/mus/ws/window_tree_host_impl.cc
+++ b/components/mus/ws/window_tree_host_impl.cc
@@ -161,6 +161,14 @@ const mojom::ViewportMetrics& WindowTreeHostImpl::GetViewportMetrics() const {
   return display_manager_->GetViewportMetrics();
 }
 
+void WindowTreeHostImpl::SetCapture(ServerWindow* window,
+                                    bool in_nonclient_area) {
+  ServerWindow* capture_window = event_dispatcher_.capture_window();
+  if (capture_window == window)
+    return;
+  event_dispatcher_.SetCaptureWindow(window, in_nonclient_area);
+}
+
 mojom::Rotation WindowTreeHostImpl::GetRotation() const {
   return display_manager_->GetRotation();
 }
@@ -343,6 +351,19 @@ void WindowTreeHostImpl::OnEvent(const ui::Event& event) {
   event_dispatcher_.ProcessEvent(std::move(mojo_event));
 }
 
+void WindowTreeHostImpl::SetCapture(ServerWindow* window) {
+  if (window)

[sky, 2016/02/10 17:38:22]

This should never supply null, right? If I'm right, then DCHECK(window). If I'm
wrong, why would we supply null?

[jonross, 2016/02/10 19:45:49]

Window is no longer passed in. So removed.

+    display_manager_->SetCapture();
+}
+
+void WindowTreeHostImpl::ReleaseCapture(ServerWindow* window) {
+  display_manager_->ReleaseCapture();
+}
+
+void WindowTreeHostImpl::OnLostCapture() {
+  SetCapture(nullptr, false);
+}
+
 void WindowTreeHostImpl::OnDisplayClosed() {
   if (delegate_)
     delegate_->OnDisplayClosed();
@@ -474,6 +495,11 @@ ServerWindow* WindowTreeHostImpl::GetFocusedWindowForEventDispatcher() {
   return GetFocusedWindow();
 }
 
+void WindowTreeHostImpl::OnLostCapture(ServerWindow* window) {
+  DCHECK(window);
+  connection_manager_->ProcessLostCapture(window);
+}
+
 void WindowTreeHostImpl::DispatchInputEventToWindow(ServerWindow* target,
                                                     bool in_nonclient_area,
                                                     mojom::EventPtr event) {