chrome: Cleanup class/struct forward declarations

chrome/browser/search/search.h

 // Copyright 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_SEARCH_SEARCH_H_
 #define CHROME_BROWSER_SEARCH_SEARCH_H_
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/strings/string16.h"
 #include "chrome/browser/ui/search/search_model.h"
 
 class GURL;
 class Profile;
 
 namespace content {
 class BrowserContext;
 class NavigationEntry;
 class WebContents;
 }
 
-namespace user_prefs {
-class PrefRegistrySyncable;
-}
-
 namespace search {
 
 // For reporting Cacheable NTP navigations.
 enum CacheableNTPLoad {
   CACHEABLE_NTP_LOAD_FAILED = 0,
   CACHEABLE_NTP_LOAD_SUCCEEDED = 1,
   CACHEABLE_NTP_LOAD_MAX = 2
 };
 
 // Returns whether the suggest is enabled for the given |profile|.
@@ skipping 94 matching lines @@
 // -----------------------------------------------------
 // The following APIs are exposed for use in tests only.
 // -----------------------------------------------------
 
 // Returns the Cacheable New Tab Page URL for the given |profile|.
 GURL GetNewTabPageURL(Profile* profile);
 
 }  // namespace search
 
 #endif  // CHROME_BROWSER_SEARCH_SEARCH_H_