chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/chrome_extensions_browser_client.h

 // Copyright 2013 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_CHROME_EXTENSIONS_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 12 matching lines @@
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
 class ChromeComponentExtensionResourceManager;
 class ChromeExtensionsAPIClient;
 class ChromeProcessManagerDelegate;
-class ContentSettingsPrefsObserver;
 
 // Implementation of BrowserClient for Chrome, which includes
 // knowledge of Profiles, BrowserContexts and incognito.
 //
 // NOTE: Methods that do not require knowledge of browser concepts should be
 // implemented in ChromeExtensionsClient even if they are only used in the
 // browser process (see chrome/common/extensions/chrome_extensions_client.h).
 class ChromeExtensionsBrowserClient : public ExtensionsBrowserClient {
  public:
   ChromeExtensionsBrowserClient();
@@ skipping 96 matching lines @@
   std::unique_ptr<ExtensionCache> extension_cache_;
 
   std::unique_ptr<KioskDelegate> kiosk_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeExtensionsBrowserClient);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CHROME_EXTENSIONS_BROWSER_CLIENT_H_