chrome: Cleanup class/struct forward declarations

chrome/browser/data_use_measurement/chrome_data_use_ascriber.h

 // Copyright 2016 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_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_H_
 #define CHROME_BROWSER_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_H_
 
 #include <list>
 #include <memory>
 #include <unordered_map>
 #include <utility>
 
 #include "base/containers/hash_tables.h"
 #include "base/hash.h"
 #include "base/macros.h"
 #include "base/supports_user_data.h"
 #include "components/data_use_measurement/core/data_use_ascriber.h"
 #include "content/public/browser/global_request_id.h"
 #include "url/gurl.h"
 
 namespace content {
-class NavigationHandle;
 class RenderFrameHost;
 }
 
 namespace data_use_measurement {
 
 class URLRequestClassifier;
 
 // Browser implementation of DataUseAscriber. Maintains a list of
 // DataUseRecorder instances, one for each source of data, such as a page
 // load.
@@ skipping 115 matching lines @@
                      DataUseRecorderEntry,
                      GlobalRequestIDHash>
       pending_navigation_data_use_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeDataUseAscriber);
 };
 
 }  // namespace data_use_measurement
 
 #endif  // CHROME_BROWSER_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_H_