chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/crx_installer.h

 // Copyright (c) 2012 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_CRX_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 19 matching lines @@
 class SkBitmap;
 struct WebApplicationInfo;
 
 namespace base {
 class SequencedTaskRunner;
 }
 
 namespace extensions {
 class CrxInstallError;
 class ExtensionUpdaterTest;
-class RequirementsChecker;
 
 // This class installs a crx file into a profile.
 //
 // Installing a CRX is a multi-step process, including unpacking the crx,
 // validating it, prompting the user, and installing. Since many of these
 // steps must occur on the file thread, this class contains a copy of all data
 // necessary to do its job. (This also minimizes external dependencies for
 // easier testing).
 //
 // Lifetime management:
@@ skipping 389 matching lines @@
 
   // Performs requirements, policy and blacklist checks on the extension.
   ExtensionInstallChecker install_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(CrxInstaller);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_