Fix video capture unit test making wrong assumption about event ordering

Bug: 872065
Change-Id: If0de2e5cb8470e604bc97f1c3689ae8972888e6c
Reviewed-on: https://chromium-review.googlesource.com/1167968Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Christian Fremerey <chfremer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581702}

services/video_capture/texture_virtual_device_mojo_adapter_unittest.cc

@@ -79,9 +79,19 @@ TEST_F(TextureVirtualDeviceMojoAdapterTest,
   ProducerSharesBufferHandle(kArbitraryBufferId2);
 
   base::RunLoop wait_loop;
-  EXPECT_CALL(*mock_receiver_1_, DoOnNewBuffer(kArbitraryBufferId1, _));
+  int buffer_received_count = 0;
+  EXPECT_CALL(*mock_receiver_1_, DoOnNewBuffer(kArbitraryBufferId1, _))
+      .WillOnce(InvokeWithoutArgs([&wait_loop, &buffer_received_count]() {
+        buffer_received_count++;
+        if (buffer_received_count == 2)
+          wait_loop.Quit();
+      }));
   EXPECT_CALL(*mock_receiver_1_, DoOnNewBuffer(kArbitraryBufferId2, _))
-      .WillOnce(InvokeWithoutArgs([&wait_loop]() { wait_loop.Quit(); }));
+      .WillOnce(InvokeWithoutArgs([&wait_loop, &buffer_received_count]() {
+        buffer_received_count++;
+        if (buffer_received_count == 2)
+          wait_loop.Quit();
+      }));
   Receiver1Connects();
   wait_loop.Run();
 }