components: Cleanup class/struct fwd declarations

components/metrics/metrics_provider.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.
 
 #ifndef COMPONENTS_METRICS_METRICS_PROVIDER_H_
 #define COMPONENTS_METRICS_METRICS_PROVIDER_H_
 
 #include "base/macros.h"
 
 namespace base {
 class HistogramSnapshotManager;
 }  // namespace base
 
 namespace metrics {
 
 class ChromeUserMetricsExtension;
 class SystemProfileProto;
-class SystemProfileProto_Stability;
 
 // MetricsProvider is an interface allowing different parts of the UMA protos to
 // be filled out by different classes.
 class MetricsProvider {
  public:
   MetricsProvider();
   virtual ~MetricsProvider();
 
   // Called after initialiazation of MetricsService and field trials.
   virtual void Init();
@@ skipping 66 matching lines @@
   virtual void RecordInitialHistogramSnapshots(
       base::HistogramSnapshotManager* snapshot_manager);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MetricsProvider);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_PROVIDER_H_