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

content/browser/webui/web_ui_data_source_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_WEBUI_WEB_UI_DATA_SOURCE_IMPL_H_
 #define CONTENT_BROWSER_WEBUI_WEB_UI_DATA_SOURCE_IMPL_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 35 matching lines @@
   void DisableReplaceExistingSource() override;
   void DisableContentSecurityPolicy() override;
   void OverrideContentSecurityPolicyObjectSrc(const std::string& data) override;
   void OverrideContentSecurityPolicyChildSrc(const std::string& data) override;
   void DisableDenyXFrameOptions() override;
   void DisableI18nAndUseGzipForAllPaths() override;
 
   // When DisableI18nAndUseGzipForAllPaths is enabled, exclude the given |path|.
   void ExcludePathFromGzip(const std::string& path);
 
+  bool IsWebUIDataSourceImpl() const override;
+
  protected:
   ~WebUIDataSourceImpl() override;
 
   // Completes a request by sending our dictionary of localized strings.
   void SendLocalizedStringsAsJSON(
       const URLDataSource::GotDataCallback& callback);
 
  private:
   class InternalDataSource;
   friend class InternalDataSource;
@@ skipping 39 matching lines @@
   bool add_load_time_data_defaults_;
   bool replace_existing_source_;
   bool use_gzip_for_all_paths_;
 
   DISALLOW_COPY_AND_ASSIGN(WebUIDataSourceImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEBUI_WEB_UI_DATA_SOURCE_IMPL_H_