events: Move the PlatformEventSource creation in aura::Env.

ui/wm/core/wm_state.h

Index: ui/wm/core/wm_state.h
diff --git a/ui/wm/core/wm_state.h b/ui/wm/core/wm_state.h
index ab5e5c260d46fd07db2f3c4e5d60dccaaa6c273a..289c9dac5b53fc3ee1b831dda33467611e7261f6 100644
--- a/ui/wm/core/wm_state.h
+++ b/ui/wm/core/wm_state.h
@@ -8,10 +8,6 @@
 #include "base/memory/scoped_ptr.h"
 #include "ui/wm/wm_export.h"
 
-namespace ui {
-class PlatformEventSource;
-}
-
 namespace wm {
 
 class TransientWindowController;
@@ -27,7 +23,6 @@ class WM_EXPORT WMState {
  private:
   scoped_ptr<TransientWindowStackingClient> window_stacking_client_;
   scoped_ptr<TransientWindowController> transient_window_client_;
-  scoped_ptr<ui::PlatformEventSource> event_source_;
 
   DISALLOW_COPY_AND_ASSIGN(WMState);
 };