MD History: update (instead of re-create) data sources on sign in change

content/browser/webui/url_data_source_impl.h

 // Copyright (c) 2013 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_WEBUI_URL_DATA_SOURCE_IMPL_H_
 #define CONTENT_BROWSER_WEBUI_URL_DATA_SOURCE_IMPL_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
@@ skipping 45 matching lines @@
 
   // Report that a request has resulted in the data |bytes|.
   // If the request can't be satisfied, pass NULL for |bytes| to indicate
   // the request is over.
   virtual void SendResponse(int request_id,
                             scoped_refptr<base::RefCountedMemory> bytes);
 
   const std::string& source_name() const { return source_name_; }
   URLDataSource* source() const { return source_.get(); }
 
+  virtual bool IsWebUIDataSourceImpl() const;
+
  protected:
   virtual ~URLDataSourceImpl();
 
  private:
   friend class URLDataManager;
   friend class URLDataManagerBackend;
   friend class base::DeleteHelper<URLDataSourceImpl>;
 
   // SendResponse invokes this on the IO thread. Notifies the backend to
   // handle the actual work of sending the data.
@@ skipping 14 matching lines @@
   // scoped_refptr else there would be a cycle between the backend and data
   // source.
   URLDataManagerBackend* backend_;
 
   std::unique_ptr<URLDataSource> source_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEBUI_URL_DATA_SOURCE_IMPL_H_