Add sidebar views implementation using ExtensionSystem SidebarManager

chrome/browser/ui/extensions/extension_action_platform_delegate.h

 // Copyright 2014 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 CHROME_BROWSER_UI_EXTENSIONS_EXTENSION_ACTION_PLATFORM_DELEGATE_H_
 #define CHROME_BROWSER_UI_EXTENSIONS_EXTENSION_ACTION_PLATFORM_DELEGATE_H_
 
 #include "chrome/browser/ui/extensions/extension_action_view_controller.h"
 
 class GURL;
@@ skipping 21 matching lines @@
   // Shows the given |host|. |grant_tab_permissions| is true if active tab
   // permissions should be given to the extension; this is only true if the
   // popup is opened through a user action.
   virtual void ShowPopup(
       scoped_ptr<extensions::ExtensionViewHost> host,
       bool grant_tab_permissions,
       ExtensionActionViewController::PopupShowAction show_action) = 0;
 
   // Closes the overflow menu, if it was open.
   virtual void CloseOverflowMenu() = 0;
+
+  // Shows a sidebar with a given |sidebar_contents|.
+  virtual void ShowSidebar(content::WebContents* sidebar_contents) = 0;
+  // Hides a sidebar if there are active one.
+  virtual void HideSidebar() = 0;
 };
 
 #endif  // CHROME_BROWSER_UI_EXTENSIONS_EXTENSION_ACTION_PLATFORM_DELEGATE_H_