ios: Cleanup class/struct forward declarations

ios/chrome/browser/metrics/ios_chrome_metrics_service_client.h

 // Copyright 2015 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 IOS_CHROME_BROWSER_METRICS_IOS_CHROME_METRICS_SERVICE_CLIENT_H_
 #define IOS_CHROME_BROWSER_METRICS_IOS_CHROME_METRICS_SERVICE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "components/metrics/metrics_service_client.h"
 #include "components/metrics/profiler/tracking_synchronizer_observer.h"
 #include "components/omnibox/browser/omnibox_event_global_tracker.h"
 #include "ios/web/public/web_state/global_web_state_observer.h"
 
 class IOSChromeStabilityMetricsProvider;
 class PrefRegistrySimple;
-class PrefService;
-
-namespace base {
-class FilePath;
-}  // namespace base
 
 namespace metrics {
 class DriveMetricsProvider;
 class MetricsService;
 class MetricsStateManager;
 class ProfilerMetricsProvider;
 }  // namespace metrics
 
 // IOSChromeMetricsServiceClient provides an implementation of
 // MetricsServiceClient that depends on //ios/chrome/.
@@ skipping 115 matching lines @@
   // Whether this client has already uploaded profiler data during this session.
   // Profiler data is uploaded at most once per session.
   bool has_uploaded_profiler_data_;
 
   base::WeakPtrFactory<IOSChromeMetricsServiceClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSChromeMetricsServiceClient);
 };
 
 #endif  // IOS_CHROME_BROWSER_METRICS_IOS_CHROME_METRICS_SERVICE_CLIENT_H_