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

content/browser/webui/url_data_manager.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_URL_DATA_MANAGER_H_
 #define CONTENT_BROWSER_WEBUI_URL_DATA_MANAGER_H_
 
+#include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/supports_user_data.h"
 #include "content/common/content_export.h"
 
+namespace base {
+class DictionaryValue;
+}
+
 namespace content {
 class BrowserContext;
 class URLDataSource;
 class URLDataSourceImpl;
 class WebUIDataSource;
 
 // To serve dynamic data off of chrome: URLs, implement the
 // URLDataManager::DataSource interface and register your handler
 // with AddDataSource. DataSources must be added on the UI thread (they are also
 // deleted on the UI thread). Internally the DataSources are maintained by
 // URLDataManagerBackend, see it for details.
 class CONTENT_EXPORT URLDataManager : public base::SupportsUserData::Data {
  public:
   explicit URLDataManager(BrowserContext* browser_context);
   ~URLDataManager() override;
 
   // Adds a DataSource to the collection of data sources. This *must* be invoked
   // on the UI thread.
   //
   // If |AddDataSource| is called more than once for a particular name it will
   // release the old |DataSource|, most likely resulting in it getting deleted
   // as there are no other references to it. |DataSource| uses the
   // |DeleteOnUIThread| trait to insure that the destructor is called on the UI
   // thread. This is necessary as some |DataSource|s notably |FileIconSource|
   // and |FaviconSource|, have members that will DCHECK if they are not
   // destructed in the same thread as they are constructed (the UI thread).
   void AddDataSource(URLDataSourceImpl* source);
 
+  void UpdateWebUIDataSource(const std::string& source_name,
+                             std::unique_ptr<base::DictionaryValue> update);
+
   // Deletes any data sources no longer referenced. This is normally invoked
   // for you, but can be invoked to force deletion (such as during shutdown).
   static void DeleteDataSources();
 
   // Convenience wrapper function to add |source| to |browser_context|'s
   // |URLDataManager|. Creates a URLDataSourceImpl to wrap the given
   // source.
   static void AddDataSource(BrowserContext* browser_context,
                             URLDataSource* source);
 
   // Adds a WebUI data source to |browser_context|'s |URLDataManager|.
   static void AddWebUIDataSource(BrowserContext* browser_context,
                                  WebUIDataSource* source);
 
+  // Updates an existing WebUI data source.
+  static void UpdateWebUIDataSource(
+      BrowserContext* browser_context,
+      const std::string& source_name,
+      std::unique_ptr<base::DictionaryValue> update);
+
  private:
   friend class URLDataSourceImpl;
   friend struct DeleteURLDataSource;
   typedef std::vector<const URLDataSourceImpl*> URLDataSources;
 
   // If invoked on the UI thread the DataSource is deleted immediatlye,
   // otherwise it is added to |data_sources_| and a task is scheduled to handle
   // deletion on the UI thread. See note abouve DeleteDataSource for more info.
   static void DeleteDataSource(const URLDataSourceImpl* data_source);
 
   // Returns true if |data_source| is scheduled for deletion (|DeleteDataSource|
   // was invoked).
   static bool IsScheduledForDeletion(const URLDataSourceImpl* data_source);
 
   BrowserContext* browser_context_;
 
   // |data_sources_| that are no longer referenced and scheduled for deletion.
   // Protected by g_delete_lock in the .cc file.
   static URLDataSources* data_sources_;
 
   DISALLOW_COPY_AND_ASSIGN(URLDataManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEBUI_URL_DATA_MANAGER_H_