Desktop Aura: Allow tab drags out of window.

ui/aura/root_window_host_delegate.h

Index: ui/aura/root_window_host_delegate.h
diff --git a/ui/aura/root_window_host_delegate.h b/ui/aura/root_window_host_delegate.h
index 6bc58522803b38052659a659536bb375b4046a64..13c4f714f2d79977b51b2c5d3dec369c8d95b267 100644
--- a/ui/aura/root_window_host_delegate.h
+++ b/ui/aura/root_window_host_delegate.h
@@ -6,6 +6,7 @@
 #define UI_AURA_ROOT_WINDOW_HOST_DELEGATE_H_
 
 namespace gfx {
+class Point;
 class Size;
 }
 
@@ -33,6 +34,7 @@ class AURA_EXPORT RootWindowHostDelegate {
 
   virtual void OnHostPaint() = 0;
 
+  virtual void OnHostMoved(const gfx::Point& origin) = 0;
   virtual void OnHostResized(const gfx::Size& size) = 0;
 
   virtual float GetDeviceScaleFactor() = 0;