aura: Add X11 host window management.

ui/aura/root_window_host_mac.mm

Index: ui/aura/root_window_host_mac.mm
diff --git a/ui/aura/root_window_host_mac.mm b/ui/aura/root_window_host_mac.mm
index 4c9f69aba826386f60a96cc4c5b06759810f300d..5c603c34220f1c68967ce99ac5fe6750d8c1c315 100644
--- a/ui/aura/root_window_host_mac.mm
+++ b/ui/aura/root_window_host_mac.mm
@@ -32,6 +32,7 @@ class RootWindowHostMac : public RootWindowHost,
   // RootWindowHost:
   virtual void SetRootWindow(RootWindow* root_window) OVERRIDE;
   virtual gfx::AcceleratedWidget GetAcceleratedWidget() OVERRIDE;
+  virtual gfx::AcceleratedWidget GetAcceleratedWidgetUsedForEvents() OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void ToggleFullScreen() OVERRIDE;
   virtual gfx::Size GetSize() const OVERRIDE;
@@ -123,6 +124,11 @@ gfx::AcceleratedWidget RootWindowHostMac::GetAcceleratedWidget() {
   return [[controller_ window] contentView];
 }
 
+gfx::AcceleratedWidget RootWindowHostMac::
+    GetAcceleratedWidgetUsedForEvents() {
+  return [[controller_ window] contentView];
+}
+
 void RootWindowHostMac::Show() {
   [controller_ showWindow:controller_];
 }