Moving extension code out of "components/" to avoid layering violations.

chrome/browser/renderer_context_menu/context_menu_content_type_platform_app.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_RENDERER_CONTEXT_MENU_CONTEXT_MENU_CONTENT_TYPE_PLATFORM_APP_H_
 #define CHROME_BROWSER_RENDERER_CONTEXT_MENU_CONTEXT_MENU_CONTENT_TYPE_PLATFORM_APP_H_
 
 #include "components/renderer_context_menu/context_menu_content_type.h"
 
+namespace extensions {
+class Extension;
+}
+
 class ContextMenuContentTypePlatformApp : public ContextMenuContentType {
  public:
   ~ContextMenuContentTypePlatformApp() override;
 
   // ContextMenuContentType overrides.
   bool SupportsGroup(int group) override;
 
  protected:
   ContextMenuContentTypePlatformApp(content::WebContents* web_contents,
                                     const content::ContextMenuParams& params);
 
  private:
   friend class ContextMenuContentTypeFactory;
 
+  const extensions::Extension* GetExtension() const;
+
   DISALLOW_COPY_AND_ASSIGN(ContextMenuContentTypePlatformApp);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_CONTEXT_MENU_CONTEXT_MENU_CONTENT_TYPE_PLATFORM_APP_H_