Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc

 // 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.
 
 #include "chrome/browser/ui/gtk/tabs/tab_renderer_gtk.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/debug/trace_event.h"
@@ skipping 315 matching lines @@
                                 bool loading_only) {
   DCHECK(contents);
   TabContents* tab_contents = TabContents::FromWebContents(contents);
 
   if (!loading_only) {
     data_.title = contents->GetTitle();
     data_.incognito = contents->GetBrowserContext()->IsOffTheRecord();
     data_.crashed = contents->IsCrashed();
 
     SkBitmap* app_icon =
-        tab_contents->extension_tab_helper()->GetExtensionAppIcon();
+        extensions::TabHelper::FromWebContents(contents)->GetExtensionAppIcon();
     if (app_icon) {
       data_.favicon = *app_icon;
     } else {
       data_.favicon =
           tab_contents->favicon_tab_helper()->GetFavicon().AsBitmap();
     }
 
     data_.app = app;
 
     // Make a cairo cached version of the favicon.
@@ skipping 774 matching lines @@
   GdkPixbuf* tab_close = rb.GetNativeImageNamed(IDR_TAB_CLOSE).ToGdkPixbuf();
   close_button_width_ = gdk_pixbuf_get_width(tab_close);
   close_button_height_ = gdk_pixbuf_get_height(tab_close);
 
   const gfx::Font& base_font = rb.GetFont(ui::ResourceBundle::BaseFont);
   title_font_ = new gfx::Font(base_font.GetFontName(), kFontPixelSize);
   title_font_height_ = title_font_->GetHeight();
 
   initialized_ = true;
 }