mus: Add EventObserver to allow passively listening to UI events

components/mus/ws/window_server.cc

Index: components/mus/ws/window_server.cc
diff --git a/components/mus/ws/window_server.cc b/components/mus/ws/window_server.cc
index 6d73462cafb6f96f7ac2699338ae23c3cb51f02b..2bfa02f1b44f8e7e32a35beea6ead1a6ed9bf1bf 100644
--- a/components/mus/ws/window_server.cc
+++ b/components/mus/ws/window_server.cc
@@ -399,6 +399,12 @@ void WindowServer::ProcessWillChangeWindowPredefinedCursor(ServerWindow* window,
     display->OnCursorUpdated(window);
 }
 
+void WindowServer::SendToEventObservers(const ui::Event& event) {
+  for (auto& pair : tree_map_) {

[sky, 2016/04/21 17:23:04]

nit: no {}

[James Cook, 2016/04/22 18:22:54]

Done.

+    pair.second->SendToEventObserver(event);
+  }

[sadrul, 2016/04/21 19:15:29]

It should send only if the requestor and the target of |event| is the same user.

[James Cook, 2016/04/22 18:22:54]

Done.

+}
+
 void WindowServer::ProcessViewportMetricsChanged(
     Display* display,
     const mojom::ViewportMetrics& old_metrics,