chrome: Cleanup class/struct forward declarations

chrome/browser/predictors/resource_prefetcher_manager.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 CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/predictors/resource_prefetch_common.h"
 #include "chrome/browser/predictors/resource_prefetcher.h"
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace predictors {
 
-struct NavigationID;
 class ResourcePrefetchPredictor;
 
 // Manages prefetches for multiple navigations.
 //  - Created and owned by the resource prefetch predictor.
 //  - Needs to be refcounted as it is de-referenced on two different threads.
 //  - Created on the UI thread, but most functions are called in the IO thread.
 //  - Will only allow one inflight prefresh per host.
 class ResourcePrefetcherManager
     :  public ResourcePrefetcher::Delegate,
        public base::RefCountedThreadSafe<ResourcePrefetcherManager> {
@@ skipping 35 matching lines @@
   net::URLRequestContextGetter* const context_getter_;
 
   std::map<std::string, std::unique_ptr<ResourcePrefetcher>> prefetcher_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetcherManager);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_