Webview tag creation should be using storage partitions.

content/browser/web_contents/web_contents_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 75 matching lines @@
 
   static WebContentsImpl* CreateWithOpener(
       BrowserContext* browser_context,
       SiteInstance* site_instance,
       int routing_id,
       const WebContentsImpl* base_web_contents,
       WebContentsImpl* opener);
 
   // Creates a WebContents to be used as a browser plugin guest.
   static WebContentsImpl* CreateGuest(BrowserContext* browser_context,
-                                      const std::string& host,
+                                      SiteInstance* site_instance,
                                       int guest_instance_id,
                                       bool focused,
                                       bool visible);
 
   // Returns the content specific prefs for the given RVH.
   static webkit_glue::WebPreferences GetWebkitPrefs(
       RenderViewHost* rvh, const GURL& url);
 
   // Creates a swapped out RenderView. This is used by the browser plugin to
   // create a swapped out RenderView in the embedder render process for the
@@ skipping 747 matching lines @@
   // All live RenderWidgetHostImpls that are created by this object and may
   // outlive it.
   std::set<RenderWidgetHostImpl*> created_widgets_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_