extensions: Cleanup class/struct fwd declarations

extensions/shell/browser/shell_browser_context.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 EXTENSIONS_SHELL_BROWSER_SHELL_BROWSER_CONTEXT_H_
 #define EXTENSIONS_SHELL_BROWSER_SHELL_BROWSER_CONTEXT_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "content/shell/browser/shell_browser_context.h"
 #include "storage/browser/quota/special_storage_policy.h"
 
 namespace extensions {
 
-class InfoMap;
 class ShellBrowserMainParts;
-class ShellSpecialStoragePolicy;
 
 // The BrowserContext used by the content, apps and extensions systems in
 // app_shell.
 class ShellBrowserContext : public content::ShellBrowserContext {
  public:
   explicit ShellBrowserContext(ShellBrowserMainParts* browser_main_parts);
   ~ShellBrowserContext() override;
 
   // content::BrowserContext implementation.
   content::BrowserPluginGuestManager* GetGuestManager() override;
   storage::SpecialStoragePolicy* GetSpecialStoragePolicy() override;
   net::URLRequestContextGetter* CreateRequestContext(
       content::ProtocolHandlerMap* protocol_handlers,
       content::URLRequestInterceptorScopedVector request_interceptors) override;
 
  private:
   void InitURLRequestContextOnIOThread();
 
   scoped_refptr<storage::SpecialStoragePolicy> storage_policy_;
   ShellBrowserMainParts* browser_main_parts_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellBrowserContext);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_SHELL_BROWSER_SHELL_BROWSER_CONTEXT_H_