components: Cleanup class/struct fwd declarations

components/metrics/file_metrics_provider.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 COMPONENTS_METRICS_FILE_METRICS_PROVIDER_H_
 #define COMPONENTS_METRICS_FILE_METRICS_PROVIDER_H_
 
 #include <list>
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "components/metrics/metrics_provider.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace base {
-class MemoryMappedFile;
-class PersistentMemoryAllocator;
 class TaskRunner;
 }
 
 namespace metrics {
 
 // FileMetricsProvider gathers and logs histograms written to files on disk.
 // Any number of files can be registered and will be polled once per upload
 // cycle (at startup and periodically thereafter -- about every 30 minutes
 // for desktop) for data to send.
 class FileMetricsProvider : public MetricsProvider {
@@ skipping 161 matching lines @@
 
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<FileMetricsProvider> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FileMetricsProvider);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_FILE_METRICS_PROVIDER_H_