Move Mus into chrome's process when running with --mus.

ui/events/platform/platform_event_source.h

Index: ui/events/platform/platform_event_source.h
diff --git a/ui/events/platform/platform_event_source.h b/ui/events/platform/platform_event_source.h
index 3f16bd603bc998ab49ec28962d9602b09b3ab502..b4e3084dd1fb23b36c7319c8ddd6bd03231fec04 100644
--- a/ui/events/platform/platform_event_source.h
+++ b/ui/events/platform/platform_event_source.h
@@ -33,6 +33,7 @@ class EVENTS_EXPORT PlatformEventSource {
  public:
   virtual ~PlatformEventSource();
 
+  // Returns the thread-local singleton.
   static PlatformEventSource* GetInstance();
 
   // Adds a dispatcher to the dispatcher list. If a dispatcher is added during
@@ -64,6 +65,7 @@ class EVENTS_EXPORT PlatformEventSource {
   void AddPlatformEventObserver(PlatformEventObserver* observer);
   void RemovePlatformEventObserver(PlatformEventObserver* observer);
 
+  // Creates PlatformEventSource and sets it as a thread-local singleton.
   static std::unique_ptr<PlatformEventSource> CreateDefault();
 
  protected:
@@ -80,8 +82,6 @@ class EVENTS_EXPORT PlatformEventSource {
   friend class ScopedEventDispatcher;
   friend class test::PlatformEventSourceTestAPI;
 
-  static PlatformEventSource* instance_;
-
   // This is invoked when the list of dispatchers changes (i.e. a new dispatcher
   // is added, or a dispatcher is removed).
   virtual void OnDispatcherListChanged();