Replace MessageLoop::current()->task_runner() with ThreadTaskRunnerHandle::Get().

ash/shelf/shelf_view_unittest.cc

Index: ash/shelf/shelf_view_unittest.cc
diff --git a/ash/shelf/shelf_view_unittest.cc b/ash/shelf/shelf_view_unittest.cc
index 45c6a5cc51357a7af0663f8b34968f610396ecda..ba3874cd940a920003188ed5917dc5a3e49fc0b3 100644
--- a/ash/shelf/shelf_view_unittest.cc
+++ b/ash/shelf/shelf_view_unittest.cc
@@ -2624,12 +2624,12 @@ class ScopedMockTaskRunnerWrapper {
  public:
   ScopedMockTaskRunnerWrapper() {
     mock_task_runner_ = new base::TestMockTimeTaskRunner;
-    previous_task_runner_ = base::MessageLoop::current()->task_runner();
+    previous_task_runner_ = base::ThreadTaskRunnerHandle::Get();
     base::MessageLoop::current()->SetTaskRunner(mock_task_runner_);
   }
 
   ~ScopedMockTaskRunnerWrapper() {
-    DCHECK_EQ(mock_task_runner_, base::MessageLoop::current()->task_runner());
+    DCHECK_EQ(mock_task_runner_, base::ThreadTaskRunnerHandle::Get());
     mock_task_runner_->ClearPendingTasks();
     base::MessageLoop::current()->SetTaskRunner(previous_task_runner_);
   }