Remove usage of ScopedAsyncTaskScheduler from bluetooth_socket_bluez_unittest.cc.

ScopedAsyncTaskScheduler is deprecated.

Bug: 708584
Change-Id: If09d3f1395fd46bcc2394d91096c3eae54bf932b
Reviewed-on: https://chromium-review.googlesource.com/592163
Commit-Queue: Rahul Chaturvedi <rkc@chromium.org>
Reviewed-by: Rahul Chaturvedi <rkc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490820}

device/bluetooth/bluez/bluetooth_socket_bluez_unittest.cc

@@ -8,9 +8,8 @@
 
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
-#include "base/test/scoped_async_task_scheduler.h"
+#include "base/test/scoped_task_environment.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_adapter_factory.h"
 #include "device/bluetooth/bluetooth_device.h"
@@ -173,8 +172,7 @@ class BluetoothSocketBlueZTest : public testing::Test {
   void ImmediateSuccessCallback() { ++success_callback_count_; }
 
  protected:
-  base::MessageLoop message_loop_;
-  base::test::ScopedAsyncTaskScheduler scoped_async_task_scheduler_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 
   scoped_refptr<BluetoothAdapter> adapter_;