chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/extension_garbage_collector_factory.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_EXTENSIONS_EXTENSION_GARBAGE_COLLECTOR_FACTORY_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_GARBAGE_COLLECTOR_FACTORY_H_
 
 #include "base/macros.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace base {
 template <typename T>
 struct DefaultSingletonTraits;
 }
 
-class Profile;
-
 namespace extensions {
 
 class ExtensionGarbageCollector;
 
 class ExtensionGarbageCollectorFactory
     : public BrowserContextKeyedServiceFactory {
  public:
   static ExtensionGarbageCollector* GetForBrowserContext(
       content::BrowserContext* context);
 
@@ skipping 14 matching lines @@
 
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionGarbageCollectorFactory);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_GARBAGE_COLLECTOR_FACTORY_H_