Makes MouseWatcher work while in metro mode

ui/views/widget/desktop_aura/desktop_native_widget_aura.cc

Index: ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
diff --git a/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc b/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
index 5ad3817e9dbdbb0a1950fd645588514a6337a9f3..5e6aee5e7c6b3104b99ec2a98f23048742de53df 100644
--- a/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
+++ b/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
@@ -42,6 +42,7 @@
 #include "ui/views/widget/desktop_aura/desktop_capture_client.h"
 #include "ui/views/widget/desktop_aura/desktop_cursor_loader_updater.h"
 #include "ui/views/widget/desktop_aura/desktop_dispatcher_client.h"
+#include "ui/views/widget/desktop_aura/desktop_event_client.h"
 #include "ui/views/widget/desktop_aura/desktop_focus_rules.h"
 #include "ui/views/widget/desktop_aura/desktop_native_cursor_manager.h"
 #include "ui/views/widget/desktop_aura/desktop_root_window_host.h"
@@ -276,6 +277,9 @@ void DesktopNativeWidgetAura::OnDesktopRootWindowHostDestroyed(
 
   aura::client::SetDragDropClient(root, NULL);
   drag_drop_client_.reset();
+
+  aura::client::SetEventClient(root, NULL);
+  event_client_.reset();
 }
 
 void DesktopNativeWidgetAura::HandleActivationChanged(bool active) {
@@ -436,6 +440,9 @@ void DesktopNativeWidgetAura::InitNativeWidget(
     root_window_->AddPreTargetHandler(focus_manager->GetEventHandler());
   }
 
+  event_client_.reset(new DesktopEventClient);
+  aura::client::SetEventClient(root_window_.get(), event_client_.get());
+
   aura::client::GetFocusClient(content_window_)->FocusWindow(content_window_);
 
   aura::client::SetActivationDelegate(content_window_, this);