WifiDataProviderChromeOs: Call NetworkHandler from correct task runner.

device/geolocation/wifi_data_provider_chromeos.h

 // Copyright (c) 2011 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 DEVICE_GEOLOCATION_WIFI_DATA_PROVIDER_CHROMEOS_H_
 #define DEVICE_GEOLOCATION_WIFI_DATA_PROVIDER_CHROMEOS_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "device/geolocation/wifi_data_provider.h"
 #include "device/geolocation/wifi_polling_policy.h"
 
-namespace base {
-class SingleThreadTaskRunner;
-}
-
 namespace device {
 
 class DEVICE_GEOLOCATION_EXPORT WifiDataProviderChromeOs
     : public WifiDataProvider {
  public:
   WifiDataProviderChromeOs();
 
   // WifiDataProvider
   void StartDataProvider() override;
   void StopDataProvider() override;
   bool GetData(WifiData* data) override;
 
  private:
   friend class GeolocationChromeOsWifiDataProviderTest;
   ~WifiDataProviderChromeOs() override;
 
-  // UI thread
-  void DoWifiScanTaskOnUIThread();  // The polling task
-  void DoStartTaskOnUIThread();
+  // NetworkHandler thread
+  void DoWifiScanTaskOnNetworkHandlerThread();
 
   // Client thread
   void DidWifiScanTaskNoResults();
   void DidWifiScanTask(const WifiData& new_data);
 
   // Will schedule a scan; i.e. enqueue DoWifiScanTask deferred task.
   void ScheduleNextScan(int interval);
 
   // Will schedule starting of the scanning process.
   void ScheduleStart();
 
   // Will schedule stopping of the scanning process.
   void ScheduleStop();
 
   // Get access point data from chromeos.
   bool GetAccessPointData(WifiData::AccessPointDataSet* data);
 
   // Controls the polling update interval. (client thread)
   std::unique_ptr<WifiPollingPolicy> polling_policy_;
 
   // The latest wifi data. (client thread)
   WifiData wifi_data_;
 
   // Whether we have strated the data provider. (client thread)
   bool started_;
 
   // Whether we've successfully completed a scan for WiFi data. (client thread)
   bool is_first_scan_complete_;
 
-  // Used to PostTask()s from the geolocation thread to creation thread.
-  const scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
-
   DISALLOW_COPY_AND_ASSIGN(WifiDataProviderChromeOs);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_GEOLOCATION_WIFI_DATA_PROVIDER_CHROMEOS_H_