Makes PlatformEventSource creation in Env conditional

ui/aura/env.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_AURA_ENV_H_
 #define UI_AURA_ENV_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "ui/aura/aura_export.h"
@@ skipping 14 matching lines @@
 class InputStateLookup;
 class Window;
 class WindowTreeHost;
 
 // A singleton object that tracks general state within Aura.
 class AURA_EXPORT Env : public ui::EventTarget {
  public:
   Env();
   virtual ~Env();
 
-  static void CreateInstance();
+  // Creates the single Env instance (if it hasn't been created yet). If
+  // |create_event_source| is true a PlatformEventSource is created.
+  // TODO(sky): nuke |create_event_source|. Only necessary while mojo's
+  // nativeviewportservice lives in the same process as the viewmanager.
+  static void CreateInstance(bool create_event_source);
   static Env* GetInstance();
   static void DeleteInstance();
 
   void AddObserver(EnvObserver* observer);
   void RemoveObserver(EnvObserver* observer);
 
   const int mouse_button_flags() const { return mouse_button_flags_; }
   void set_mouse_button_flags(int mouse_button_flags) {
     mouse_button_flags_ = mouse_button_flags;
   }
@@ skipping 10 matching lines @@
 
   // Whether any touch device is currently down.
   bool is_touch_down() const { return is_touch_down_; }
   void set_touch_down(bool value) { is_touch_down_ = value; }
 
  private:
   friend class test::EnvTestHelper;
   friend class Window;
   friend class WindowTreeHost;
 
-  void Init();
+  // See description of CreateInstance() for deatils of |create_event_source|.
+  void Init(bool create_event_source);
 
   // Called by the Window when it is initialized. Notifies observers.
   void NotifyWindowInitialized(Window* window);
 
   // Called by the WindowTreeHost when it is initialized. Notifies observers.
   void NotifyHostInitialized(WindowTreeHost* host);
 
   // Invoked by WindowTreeHost when it is activated. Notifies observers.
   void NotifyHostActivated(WindowTreeHost* host);
 
@@ skipping 13 matching lines @@
 
   scoped_ptr<InputStateLookup> input_state_lookup_;
   scoped_ptr<ui::PlatformEventSource> event_source_;
 
   DISALLOW_COPY_AND_ASSIGN(Env);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ENV_H_