Switch Extensions::TabHelper to use WebContents, WebContentsUserData.

content/browser/web_contents/web_contents_impl.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 "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 1018 matching lines @@
 }
 
 WebContents* WebContentsImpl::Clone() {
   // We use our current SiteInstance since the cloned entry will use it anyway.
   // We pass |this| for the |base_web_contents| to size the view correctly, and
   // our own opener so that the cloned page can access it if it was before.
   WebContentsImpl* tc = CreateWithOpener(GetBrowserContext(),
                                          GetSiteInstance(), MSG_ROUTING_NONE,
                                          this, opener_);
   tc->GetController().CopyStateFrom(controller_);
+  FOR_EACH_OBSERVER(WebContentsObserver,
+                    observers_,
+                    DidCloneToNewWebContents(this, tc));
   return tc;
 }
 
 gfx::NativeView WebContentsImpl::GetContentNativeView() const {
   return view_->GetContentNativeView();
 }
 
 gfx::NativeView WebContentsImpl::GetNativeView() const {
   return view_->GetNativeView();
 }
@@ skipping 2235 matching lines @@
       old_browser_plugin_host()->embedder_render_process_host();
   *embedder_container_id = old_browser_plugin_host()->instance_id();
   int embedder_process_id =
       embedder_render_process_host ? embedder_render_process_host->GetID() : -1;
   if (embedder_process_id != -1) {
     *embedder_channel_name =
         StringPrintf("%d.r%d", render_view_host->GetProcess()->GetID(),
                      embedder_process_id);
   }
 }