Add zoom extension API

chrome/browser/tab_contents/tab_contents.h

 // Copyright (c) 2011 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_TAB_CONTENTS_TAB_CONTENTS_H_
 #define CHROME_BROWSER_TAB_CONTENTS_TAB_CONTENTS_H_
 #pragma once
 
 #include <deque>
 #include <map>
@@ skipping 663 matching lines @@
 
   // Updates history with the specified navigation. This is called by
   // OnMsgNavigate to update history state.
   void UpdateHistoryForNavigation(
       scoped_refptr<history::HistoryAddPageArgs> add_page_args);
 
   // Sends the page title to the history service. This is called when we receive
   // the page title and we know we want to update history.
   void UpdateHistoryPageTitle(const NavigationEntry& entry);
 
+  // Sets the zoom level for this tab. Returns a request id that can
+  // be used to observe the corresponding ZOOM_LEVEL_CHANGED notification.
+  int SetZoomLevel(double zoom_level);
+
   // Gets the zoom level for this tab.
   double GetZoomLevel() const;
 
+  // Sets the zoom percent for this tab. Returns a request id that can
+  // be used to observe the corresponding ZOOM_LEVEL_CHANGED notification.
+  int SetZoomPercent(double zoom_percent);
+
   // Gets the zoom percent for this tab.
-  int GetZoomPercent(bool* enable_increment, bool* enable_decrement);
+  double GetZoomPercent(bool* enable_increment, bool* enable_decrement);
 
   // Shows a fade effect over this tab contents. Repeated calls will be ignored
   // until the fade is canceled. If |animate| is true the fade should animate.
   void FadeForInstant(bool animate);
 
   // Immediately removes the fade.
   void CancelInstantFade();
 
   // Opens view-source tab for this contents.
   void ViewSource();
@@ skipping 548 matching lines @@
   ObserverList<TabContentsObserver> observers_;
 
   // Content restrictions, used to disable print/copy etc based on content's
   // (full-page plugins for now only) permissions.
   int content_restrictions_;
 
   DISALLOW_COPY_AND_ASSIGN(TabContents);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_TAB_CONTENTS_H_