Remove all ReadingList entries on managed account signout.

components/reading_list/ios/favicon_web_state_dispatcher.h

 // Copyright 2016 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 COMPONENTS_READING_LIST_IOS_FAVICON_WEB_STATE_DISPATCHER_H_
 #define COMPONENTS_READING_LIST_IOS_FAVICON_WEB_STATE_DISPATCHER_H_
 
 namespace web {
 class WebState;
 }
 
 namespace reading_list {
 
 // Dispatcher for WebState having a Favicon Driver, with BookmarkModel and
 // HistoryService attached, as observer. After a WebState is returned, the
 // dispatcher keeps it alive long enough for it to download the favicons.
 class FaviconWebStateDispatcher {
  public:
   FaviconWebStateDispatcher() {}
   virtual ~FaviconWebStateDispatcher() {}
   // Returns a WebState with a Favicon Driver attached.
   virtual std::unique_ptr<web::WebState> RequestWebState() = 0;
   // Called to return a WebState. The WebState should not be used after being
   // returned.
   virtual void ReturnWebState(std::unique_ptr<web::WebState> web_state) = 0;
 
+  // Releases all the WebState currently retained for favicon fetching.
+  virtual void ReleaseAll() = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(FaviconWebStateDispatcher);
 };
 
 }  // namespace reading_list
 
 #endif  // COMPONENTS_READING_LIST_IOS_FAVICON_WEB_STATE_DISPATCHER_H_