[Metrics] Make MetricsStateManager take a callback param to check if UMA is enabled.

chrome/browser/metrics/metrics_services_manager.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 CHROME_BROWSER_METRICS_METRICS_SERVICES_MANAGER_H_
 #define CHROME_BROWSER_METRICS_METRICS_SERVICES_MANAGER_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread_checker.h"
@@ skipping 27 matching lines @@
 
   // Returns the GetRapporService, creating it if it hasn't been created yet.
   rappor::RapporService* GetRapporService();
 
   // Returns the VariationsService, creating it if it hasn't been created yet.
   chrome_variations::VariationsService* GetVariationsService();
 
  private:
   metrics::MetricsStateManager* GetMetricsStateManager();
 
+  // Returns true iff metrics reporting is enabled.
+  bool IsMetricsReportingEnabled() const;
+
   // Ensures that all functions are called from the same thread.
   base::ThreadChecker thread_checker_;
 
   // Weak pointer to the local state prefs store.
   PrefService* local_state_;
 
   // MetricsStateManager which is passed as a parameter to service constructors.
   scoped_ptr<metrics::MetricsStateManager> metrics_state_manager_;
 
   // The MetricsService, used for UMA report uploads.
   scoped_ptr<MetricsService> metrics_service_;
 
   // The RapporService, for RAPPOR metric uploads.
   scoped_ptr<rappor::RapporService> rappor_service_;
 
   // The VariationsService, for server-side experiments infrastructure.
   scoped_ptr<chrome_variations::VariationsService> variations_service_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsServicesManager);
 };
 
 #endif  // CHROME_BROWSER_METRICS_METRICS_SERVICES_MANAGER_H_