re-use WebUIs

chrome/browser/ui/webui/ntp/new_tab_ui.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 "build/build_config.h"
 
 #include "chrome/browser/ui/webui/ntp/new_tab_ui.h"
 
 #include <set>
 
@@ skipping 187 matching lines @@
     // Some more paints must've occurred since we set the timeout.
     // Wait some more.
     timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(kTimeoutMs), this,
                  &NewTabUI::PaintTimeout);
   }
 }
 
 void NewTabUI::StartTimingPaint(RenderViewHost* render_view_host) {
   start_ = base::TimeTicks::Now();
   last_paint_ = start_;
-  registrar_.Add(this, content::NOTIFICATION_RENDER_WIDGET_HOST_DID_PAINT,
-                 content::Source<content::RenderWidgetHost>(render_view_host));
+
+  content::NotificationSource source =
+      content::Source<content::RenderWidgetHost>(render_view_host);
+  if (!registrar_.IsRegistered(this,
+          content::NOTIFICATION_RENDER_WIDGET_HOST_DID_PAINT,
+          source)) {
+    registrar_.Add(this, content::NOTIFICATION_RENDER_WIDGET_HOST_DID_PAINT,
+                   source);
+  }
+
   timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(kTimeoutMs), this,
                &NewTabUI::PaintTimeout);
-
 }
 
 bool NewTabUI::CanShowBookmarkBar() const {
   PrefService* prefs = GetProfile()->GetPrefs();
   bool disabled_by_policy =
       prefs->IsManagedPreference(prefs::kShowBookmarkBar) &&
       !prefs->GetBoolean(prefs::kShowBookmarkBar);
   return browser_defaults::bookmarks_enabled && !disabled_by_policy;
 }
 
@@ skipping 200 matching lines @@
 }
 
 void NewTabUI::NewTabHTMLSource::AddResource(const char* resource,
                                              const char* mime_type,
                                              int resource_id) {
   DCHECK(resource);
   DCHECK(mime_type);
   resource_map_[std::string(resource)] =
       std::make_pair(std::string(mime_type), resource_id);
 }