Remove knowledge of extensions from TabRestoreServiceHelper

components/sessions/core/tab_restore_service_client.h

 // Copyright 2015 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_SESSIONS_CORE_TAB_RESTORE_SERVICE_CLIENT_H_
 #define COMPONENTS_SESSIONS_CORE_TAB_RESTORE_SERVICE_CLIENT_H_
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 55 matching lines @@
   // Note that |host_desktop_type| is opaque to the component; the only values
   // that will be passed here are those that have been passed *in* to the
   // component from the embedder via TabRestoreService.
   virtual TabRestoreServiceDelegate* FindTabRestoreServiceDelegateWithID(
       SessionID::id_type desired_id,
       int host_desktop_type) = 0;
 
   // Returns whether a given URL should be tracked for restoring.
   virtual bool ShouldTrackURLForRestore(const GURL& url) = 0;
 
+  // Returns the extension app ID for the given WebContents, or the empty string
+  // if there is no such ID (e.g., if extensions are not supported by the
+  // embedder).
+  // TODO(blundell): Replace the usage of WebContents here with the cross-
+  // platform interface that will abstract it. crbug.com/530174
+  virtual std::string GetExtensionAppIDForWebContents(
+      content::WebContents* web_contents) = 0;
+
   // Get the sequenced worker pool for running tasks on the backend thread as
   // long as the system is not shutting down.
   virtual base::SequencedWorkerPool* GetBlockingPool() = 0;
 
   // Returns the path of the directory to save state into.
   virtual base::FilePath GetPathToSaveTo() = 0;
 
   // Returns the URL that corresponds to the new tab page.
   virtual GURL GetNewTabURL() = 0;
 
   // Returns whether there is a previous session to load.
   virtual bool HasLastSession() = 0;
 
   // Fetches the contents of the last session, notifying the callback when
   // done. If the callback is supplied an empty vector of SessionWindows
   // it means the session could not be restored.
   virtual void GetLastSession(const GetLastSessionCallback& callback,
                               base::CancelableTaskTracker* tracker) = 0;
 
   // Called when a tab is restored. |url| is the URL that the tab is currently
   // visiting.
   virtual void OnTabRestored(const GURL& url) {}
 };
 
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_CORE_TAB_RESTORE_SERVICE_CLIENT_H_