Desktop Aura: Allow tab drags out of window.

ui/views/widget/widget.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_VIEWS_WIDGET_WIDGET_H_
 #define UI_VIEWS_WIDGET_WIDGET_H_
 
 #include <set>
 #include <stack>
 #include <vector>
@@ skipping 301 matching lines @@
   // resizing and/or repositioning as necessary. This is only useful for
   // non-child widgets.
   void SetBoundsConstrained(const gfx::Rect& bounds);
 
   // Sets whether animations that occur when visibility is changed are enabled.
   // Default is true.
   void SetVisibilityChangedAnimationsEnabled(bool value);
 
   // Starts a nested message loop that moves the window. This can be used to
   // start a window move operation from a mouse moved event. This returns when
-  // the move completes.
-  MoveLoopResult RunMoveLoop();
+  // the move completes. |drag_offset| is the offset from the top left corner
+  // of the window to the point where the cursor is dragging, and is used to
+  // offset the bounds of the window from the cursor.
+  MoveLoopResult RunMoveLoop(const gfx::Point& drag_offset);
 
   // Stops a previously started move loop. This is not immediate.
   void EndMoveLoop();
 
   // Places the widget in front of the specified widget in z-order.
   void StackAboveWidget(Widget* widget);
   void StackAbove(gfx::NativeView native_view);
   void StackAtTop();
 
   // Places the widget below the specified NativeView.
@@ skipping 461 matching lines @@
 
   // Is |root_layers_| out of date?
   bool root_layers_dirty_;
 
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_H_