Support 3f swipe for tab scrubbing

chrome/browser/ui/views/ash/tab_scrubber.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_VIEWS_ASH_TAB_SCRUBBER_H_
 #define CHROME_BROWSER_UI_VIEWS_ASH_TAB_SCRUBBER_H_
 
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "ui/base/events/event_handler.h"
 
 class Browser;
 class Tab;
 
 // Class to enable quick tab switching via Ctrl-left-drag.
 // Notes: this is experimental, and disables ctrl-clicks. It should not be
 // enabled other than through flags until we implement 3 finger drag as the
 // mechanism to invoke it. At that point we will add test coverage.
 class TabScrubber : public ui::EventHandler,
                     public content::NotificationObserver {
  public:
   static TabScrubber* GetInstance();
 
  private:
   TabScrubber();
   virtual ~TabScrubber();
 
   // ui::EventHandler overrides:
-  virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
+  virtual ui::EventResult OnScrollEvent(ui::ScrollEvent* event) OVERRIDE;
 
   // content::NotificationObserver overrides:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   Browser* GetActiveBrowser();
+  void StartScrubbing();
   void StopScrubbing();
 
   // Indicates that we are currently scrubbing.
   bool scrubbing_;
   // The browser that we are scrubbing.
   Browser* browser_;
-  // The tab that was active when we started scrubbing.
-  int initial_tab_index_;
   // The x value of the event that initiated scrubbing.
-  int initial_x_;
+  float scroll_x_;
+  float scroll_y_;
 
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(TabScrubber);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_ASH_TAB_SCRUBBER_H_