Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 1400 matching lines @@
   } else {
     [self removeTab:tab];
   }
 
   [delegate_ onTabDetachedWithContents:contents->web_contents()];
 }
 
 // A helper routine for creating an NSImageView to hold the favicon or app icon
 // for |contents|.
 - (NSImageView*)iconImageViewForContents:(TabContents*)contents {
-  BOOL isApp = contents->extension_tab_helper()->is_app();
+  extensions::TabHelper* extensions_tab_helper =
+      extensions::TabHelper::FromWebContents(contents->web_contents());
+  BOOL isApp = extensions_tab_helper->is_app();
   NSImage* image = nil;
   // Favicons come from the renderer, and the renderer draws everything in the
   // system color space.
   CGColorSpaceRef colorSpace = base::mac::GetSystemColorSpace();
   if (isApp) {
-    SkBitmap* icon = contents->extension_tab_helper()->GetExtensionAppIcon();
+    SkBitmap* icon = extensions_tab_helper->GetExtensionAppIcon();
     if (icon)
       image = gfx::SkBitmapToNSImageWithColorSpace(*icon, colorSpace);
   } else {
     image = mac::FaviconForTabContents(contents);
   }
 
   // Either we don't have a valid favicon or there was some issue converting it
   // from an SkBitmap. Either way, just show the default.
   if (!image)
     image = defaultFavicon_.get();
@@ skipping 662 matching lines @@
 NSView* GetSheetParentViewForTabContents(TabContents* tab_contents) {
   // View hierarchy of the contents view:
   // NSView  -- switchView, same for all tabs
   // +- NSView  -- TabContentsController's view
   //    +- TabContentsViewCocoa
   //
   // Changing it? Do not forget to modify
   // -[TabStripController swapInTabAtIndex:] too.
   return [tab_contents->web_contents()->GetNativeView() superview];
 }