Replace device_sensor browsertest by service unittest.

device/sensors/device_sensor_service.cc

 // 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.
 
 #include "device/sensors/device_sensor_service.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 99 matching lines @@
     data_fetcher_.reset();
   }
   is_shutdown_ = true;
 }
 
 void DeviceSensorService::SetDataFetcherForTesting(
     DataFetcherSharedMemory* test_data_fetcher) {
   if (data_fetcher_)
     data_fetcher_->Shutdown();
   data_fetcher_.reset(test_data_fetcher);
+  is_shutdown_ = false;
 }
 
 }  // namespace device