Cleanup: Prevent usage of various extension headers when extensions support is not compiled in.

chrome/browser/extensions/extension_service.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_EXTENSION_SERVICE_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_SERVICE_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 13 matching lines @@
 #include "extensions/browser/external_provider_interface.h"
 #include "extensions/browser/install_flag.h"
 #include "extensions/browser/management_policy.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/browser/uninstall_reason.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_set.h"
 #include "extensions/common/manifest.h"
 #include "sync/api/string_ordinal.h"
 
+#if !defined(ENABLE_EXTENSIONS)
+#error "Extensions must be enabled"
+#endif
+
 class ExtensionSyncService;
 class GURL;
 class HostContentSettingsMap;
 class Profile;
 
 namespace base {
 class CommandLine;
 class SequencedTaskRunner;
 class Version;
 }
@@ skipping 691 matching lines @@
                            GreylistedExtensionDisabled);
   FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                            GreylistDontEnableManuallyDisabled);
   FRIEND_TEST_ALL_PREFIXES(ExtensionServiceTest,
                            GreylistUnknownDontChange);
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionService);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_SERVICE_H_