components: Cleanup class/struct fwd declarations

components/metrics/metrics_log.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.
 
 // This file defines a set of user experience metrics data recorded by
 // the MetricsService.  This is the unit of data that is sent to the server.
 
 #ifndef COMPONENTS_METRICS_METRICS_LOG_H_
 #define COMPONENTS_METRICS_METRICS_LOG_H_
 
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "components/metrics/metrics_service_client.h"
 #include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace base {
-class DictionaryValue;
 class HistogramSamples;
 }
 
-namespace content {
-struct WebPluginInfo;
-}
-
 namespace variations {
 struct ActiveGroupId;
 }
 
 namespace metrics {
 
 class MetricsProvider;
 class MetricsServiceClient;
 
 class MetricsLog {
@@ skipping 156 matching lines @@
   const base::TimeTicks creation_time_;
 
   PrefService* local_state_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsLog);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_LOG_H_