Begin migration of art::Atomic to std::atomic.

Change-Id: I4858d9cbed95e5ca560956b9dabd976cebe68333
diff --git a/runtime/barrier_test.cc b/runtime/barrier_test.cc
index 331d0c0..086ef44 100644
--- a/runtime/barrier_test.cc
+++ b/runtime/barrier_test.cc
@@ -77,20 +77,20 @@
   barrier.Increment(self, num_threads);
   // At this point each thread should have passed through the barrier. The first count should be
   // equal to num_threads.
-  EXPECT_EQ(num_threads, count1);
+  EXPECT_EQ(num_threads, count1.LoadRelaxed());
   // Count 3 should still be zero since no thread should have gone past the second barrier.
-  EXPECT_EQ(0, count3);
+  EXPECT_EQ(0, count3.LoadRelaxed());
   // Now lets tell the threads to pass again.
   barrier.Increment(self, num_threads);
   // Count 2 should be equal to num_threads since each thread must have passed the second barrier
   // at this point.
-  EXPECT_EQ(num_threads, count2);
+  EXPECT_EQ(num_threads, count2.LoadRelaxed());
   // Wait for all the threads to finish.
   thread_pool.Wait(self, true, false);
   // All three counts should be equal to num_threads now.
-  EXPECT_EQ(count1, count2);
-  EXPECT_EQ(count2, count3);
-  EXPECT_EQ(num_threads, count3);
+  EXPECT_EQ(count1.LoadRelaxed(), count2.LoadRelaxed());
+  EXPECT_EQ(count2.LoadRelaxed(), count3.LoadRelaxed());
+  EXPECT_EQ(num_threads, count3.LoadRelaxed());
 }
 
 class CheckPassTask : public Task {
@@ -133,7 +133,7 @@
   // Wait for all the tasks to complete using the barrier.
   barrier.Increment(self, expected_total_tasks);
   // The total number of completed tasks should be equal to expected_total_tasks.
-  EXPECT_EQ(count, expected_total_tasks);
+  EXPECT_EQ(count.LoadRelaxed(), expected_total_tasks);
 }
 
 }  // namespace art