[Device Sensors] Remove BrowserThread knowledge

content/browser/device_sensors/sensor_manager_android.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 CONTENT_BROWSER_DEVICE_SENSORS_SENSOR_MANAGER_ANDROID_H_
 #define CONTENT_BROWSER_DEVICE_SENSORS_SENSOR_MANAGER_ANDROID_H_
 
 #include <memory>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
 #include "content/browser/device_sensors/device_sensors_consts.h"
 #include "content/common/content_export.h"
 #include "device/sensors/public/cpp/device_light_hardware_buffer.h"
 #include "device/sensors/public/cpp/device_motion_hardware_buffer.h"
 #include "device/sensors/public/cpp/device_orientation_hardware_buffer.h"
 
 namespace base {
 template <typename T>
 struct DefaultSingletonTraits;
 }
@@ skipping 117 matching lines @@
   bool motion_buffer_initialized_;
   bool orientation_buffer_initialized_;
   bool orientation_absolute_buffer_initialized_;
 
   base::Lock light_buffer_lock_;
   base::Lock motion_buffer_lock_;
   base::Lock orientation_buffer_lock_;
   base::Lock orientation_absolute_buffer_lock_;
 
   bool is_shutdown_;
+  base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(SensorManagerAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVICE_SENSORS_SENSOR_MANAGER_ANDROID_H_