Fix nits on metrics_services_manager_client.h

components/metrics_services_manager/metrics_services_manager_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 COMPONENTS_METRICS_SERVICES_MANAGER_METRICS_SERVICES_MANAGER_CLIENT_H_
 #define COMPONENTS_METRICS_SERVICES_MANAGER_METRICS_SERVICES_MANAGER_CLIENT_H_
 
-#include "base/callback.h"
+#include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/threading/thread_checker.h"
 
 namespace metrics {
-class MetricsService;
 class MetricsServiceClient;
 }
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace rappor {
 class RapporService;
 }
@@ skipping 32 matching lines @@
   // Returns whether metrics reporting is enabled.
   virtual bool IsMetricsReportingEnabled() = 0;
 
   // Whether the metrics services should record but not report metrics.
   virtual bool OnlyDoMetricsRecording() = 0;
 };
 
 }  // namespace metrics_services_manager
 
 #endif  // COMPONENTS_METRICS_SERVICES_MANAGER_METRICS_SERVICES_MANAGER_CLIENT_H_