Allow the user to drag an extension to the overflow menu, even when its empty

chrome/browser/ui/views/toolbar/extension_toolbar_menu_view.h

 // Copyright 2014 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_VIEWS_TOOLBAR_EXTENSION_TOOLBAR_MENU_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_TOOLBAR_EXTENSION_TOOLBAR_MENU_VIEW_H_
 
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/ui/views/toolbar/browser_actions_container_observer.h"
 #include "ui/views/view.h"
 
 class Browser;
 class BrowserActionsContainer;
 class WrenchMenu;
 
 // ExtensionToolbarMenuView is the view containing the extension actions that
 // overflowed from the BrowserActionsContainer, and is contained in and owned by
 // the wrench menu.
 // In the event that the WrenchMenu was opened for an Extension Action drag-and-
 // drop, this will also close the menu upon completion.
 class ExtensionToolbarMenuView : public views::View,
                                  public BrowserActionsContainerObserver {
  public:
   ExtensionToolbarMenuView(Browser* browser, WrenchMenu* wrench_menu);
   virtual ~ExtensionToolbarMenuView();
 
+  // Returns whether the wrench menu should show this view. This is true when
+  // either |container_| has icons to display or the menu was opened for a drag-
+  // and-drop operation.
+  bool ShouldShow();
+
   // views::View:
   virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual int GetHeightForWidth(int width) const OVERRIDE;
   virtual void Layout() OVERRIDE;
 
  private:
   // BrowserActionsContainerObserver:
   virtual void OnBrowserActionDragDone() OVERRIDE;
 
   // Closes the |wrench_menu_|.
@@ skipping 10 matching lines @@
 
   ScopedObserver<BrowserActionsContainer, BrowserActionsContainerObserver>
       browser_actions_container_observer_;
 
   base::WeakPtrFactory<ExtensionToolbarMenuView> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionToolbarMenuView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_TOOLBAR_EXTENSION_TOOLBAR_MENU_VIEW_H_