Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

chrome/browser/ui/cocoa/tabpose_window.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/tabpose_window.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <algorithm>
 
@@ skipping 439 matching lines @@
   NSRect thumb_start = GetStartRectRelativeTo(tile);
   CGFloat scale_to_start = NSWidth(thumb_start) / NSWidth(thumb_rect_);
   NSRect rect =
       ScaleRectWithOrigin(favicon_rect_, thumb_rect_.origin, scale_to_start);
   rect.origin.x += NSMinX(thumb_start) - NSMinX(thumb_rect_);
   rect.origin.y += NSMinY(thumb_start) - NSMinY(thumb_rect_);
   return rect;
 }
 
 NSImage* Tile::favicon() const {
-  if (contents_->extension_tab_helper()->is_app()) {
-    SkBitmap* bitmap = contents_->extension_tab_helper()->GetExtensionAppIcon();
+  extensions::TabHelper* extensions_tab_helper =
+      extensions::TabHelper::FromWebContents(contents_->web_contents());
+  if (extensions_tab_helper->is_app()) {
+    SkBitmap* bitmap = extensions_tab_helper->GetExtensionAppIcon();
     if (bitmap)
       return gfx::SkBitmapToNSImage(*bitmap);
   }
   return mac::FaviconForTabContents(contents_);
 }
 
 NSRect Tile::GetTitleStartRectRelativeTo(const Tile& tile) const {
   NSRect thumb_start = GetStartRectRelativeTo(tile);
   CGFloat scale_to_start = NSWidth(thumb_start) / NSWidth(thumb_rect_);
   NSRect rect =
@@ skipping 1193 matching lines @@
   tile.set_tab_contents(contents);
   ThumbnailLayer* thumbLayer = [allThumbnailLayers_ objectAtIndex:index];
   [thumbLayer setTabContents:contents];
 }
 
 - (void)tabStripModelDeleted {
   [self close];
 }
 
 @end