Refactor intra-strip panel drags by introducing PanelDragController.

chrome/browser/ui/panels/docked_panel_strip.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 CHROME_BROWSER_UI_PANELS_DOCKED_PANEL_STRIP_H_
 #define CHROME_BROWSER_UI_PANELS_DOCKED_PANEL_STRIP_H_
 #pragma once
 
 #include <list>
 #include <set>
@@ skipping 35 matching lines @@
   virtual void AddPanel(Panel* panel) OVERRIDE;
   virtual bool RemovePanel(Panel* panel) OVERRIDE;
   virtual void CloseAll() OVERRIDE;
   virtual void ResizePanelWindow(
       Panel* panel,
       const gfx::Size& preferred_window_size) OVERRIDE;
   virtual void OnPanelAttentionStateChanged(Panel* panel) OVERRIDE;
   virtual void ActivatePanel(Panel* panel) OVERRIDE;
   virtual void MinimizePanel(Panel* panel) OVERRIDE;
   virtual void RestorePanel(Panel* panel) OVERRIDE;
-
-  // Drags the given panel.
-  void StartDragging(Panel* panel);
-  void Drag(int delta_x);
-  void EndDragging(bool cancelled);
+  virtual bool CanDragPanel(Panel* panel) const OVERRIDE;
+  virtual void StartDraggingPanel(Panel* panel) OVERRIDE;
+  virtual void DragPanel(int delta_x, int delta_y) OVERRIDE;
+  virtual void EndDraggingPanel(bool cancelled) OVERRIDE;
 
   // Invoked when a panel's expansion state changes.
   void OnPanelExpansionStateChanged(Panel* panel);
 
   // Returns true if we should bring up the titlebars, given the current mouse
   // point.
   bool ShouldBringUpTitlebars(int mouse_x, int mouse_y) const;
 
   // Brings up or down the titlebars for all minimized panels.
   void BringUpOrDownTitlebars(bool bring_up);
@@ skipping 116 matching lines @@
   // Absolute minimum width and height for panels, including non-client area.
   // Should only be big enough to accomodate a close button on the reasonably
   // recognisable titlebar.
   static const int kPanelMinWidth;
   static const int kPanelMinHeight;
 
   DISALLOW_COPY_AND_ASSIGN(DockedPanelStrip);
 };
 
 #endif  // CHROME_BROWSER_UI_PANELS_DOCKED_PANEL_STRIP_H_