[Cleanup] Migrate the StatisticsProvider to use the TaskScheduler

chrome/browser/metrics/chromeos_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 CHROME_BROWSER_METRICS_CHROMEOS_METRICS_PROVIDER_H_
 #define CHROME_BROWSER_METRICS_CHROMEOS_METRICS_PROVIDER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 48 matching lines @@
   void Init() override;
   void OnDidCreateMetricsLog() override;
   void ProvideSystemProfileMetrics(
       metrics::SystemProfileProto* system_profile_proto) override;
   void ProvideStabilityMetrics(
       metrics::SystemProfileProto* system_profile_proto) override;
   void ProvideGeneralMetrics(
       metrics::ChromeUserMetricsExtension* uma_proto) override;
 
  private:
-  // Called on the FILE thread to load hardware class information.
-  void InitTaskGetHardwareClassOnFileThread();
+  // Called on a background thread to load hardware class information.
+  void InitTaskGetHardwareClassOnBackgroundThread();
 
   // Update the number of users logged into a multi-profile session.
   // If the number of users change while the log is open, the call invalidates
   // the user count value.
   void UpdateMultiProfileUserCount(
       metrics::SystemProfileProto* system_profile_proto);
 
   // Sets the Bluetooth Adapter instance used for the WriteBluetoothProto()
   // call and calls callback.
   void SetBluetoothAdapter(base::Closure callback,
@@ skipping 28 matching lines @@
   // Hardware class (e.g., hardware qualification ID). This class identifies
   // the configured system components such as CPU, WiFi adapter, etc.
   std::string hardware_class_;
 
   base::WeakPtrFactory<ChromeOSMetricsProvider> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeOSMetricsProvider);
 };
 
 #endif  // CHROME_BROWSER_METRICS_CHROMEOS_METRICS_PROVIDER_H_