Desktop Aura: Allow tab drags out of window.

ui/aura/root_window_host.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_ROOT_WINDOW_HOST_H_
 #define UI_AURA_ROOT_WINDOW_HOST_H_
 
 #include <vector>
 
 #include "base/message_loop.h"
@@ skipping 32 matching lines @@
   // there is none associated.
   static RootWindowHost* GetForAcceleratedWidget(
       gfx::AcceleratedWidget accelerated_widget);
 
   // Returns the accelerated widget.
   virtual gfx::AcceleratedWidget GetAcceleratedWidget() = 0;
 
   // Shows the RootWindowHost.
   virtual void Show() = 0;
 
+  // Hides the RootWindowHost.
+  virtual void Hide() = 0;
+
   // Toggles the host's full screen state.
   virtual void ToggleFullScreen() = 0;
 
   // Gets/Sets the size of the RootWindowHost.
   virtual gfx::Rect GetBounds() const = 0;
   virtual void SetBounds(const gfx::Rect& bounds) = 0;
 
   // Returns the location of the RootWindow on native screen.
   virtual gfx::Point GetLocationOnNativeScreen() const = 0;
 
@@ skipping 37 matching lines @@
   virtual void PostNativeEvent(const base::NativeEvent& native_event) = 0;
 #endif
 
   // Called when the device scale factor of the root window has chagned.
   virtual void OnDeviceScaleFactorChanged(float device_scale_factor) = 0;
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_HOST_H_