CrOS: Enable threaded UI compositor by default.

ui/compositor/compositor.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_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 
 #include <string>
 
 #include "base/hash_tables.h"
@@ skipping 240 matching lines @@
 // appropriately transformed texture for each transformed view in the widget's
 // view hierarchy.
 class COMPOSITOR_EXPORT Compositor
     : NON_EXPORTED_BASE(public cc::LayerTreeHostClient),
       public base::SupportsWeakPtr<Compositor> {
  public:
   Compositor(CompositorDelegate* delegate,
              gfx::AcceleratedWidget widget);
   virtual ~Compositor();
 
-  static void Initialize(bool useThread);
+  static void Initialize();
   static bool WasInitializedWithThread();
   static void Terminate();
 
   // Schedules a redraw of the layer tree associated with this compositor.
   void ScheduleDraw();
 
   // Sets the root of the layer tree drawn by this Compositor. The root layer
   // must have no parent. The compositor's root layer is reset if the root layer
   // is destroyed. NULL can be passed to reset the root layer, in which case the
   // compositor will stop drawing anything.
@@ skipping 130 matching lines @@
   bool disable_schedule_composite_;
 
   CompositorLock* compositor_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_