Fix HostFrameSinkManagerTest.

There is a use after free in recent commit. Fix it.

Bug: 742374
Change-Id: Iab561ccdc7f863a77a1c70460a87b6714894e954
Reviewed-on: https://chromium-review.googlesource.com/571323Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Commit-Queue: kylechar <kylechar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486857}

components/viz/host/host_frame_sink_manager_unittests.cc

@@ -131,10 +131,10 @@ TEST_F(HostFrameSinkManagerTest, CreateDestroyCompositorFrameSinkSupport) {
       nullptr /* client */, kFrameSinkId1, true /* is_root */,
       true /* handles_frame_sink_id_invalidation */,
       false /* needs_sync_points */);
-  EXPECT_TRUE(FrameSinkIdExists(support->frame_sink_id()));
+  EXPECT_TRUE(FrameSinkIdExists(kFrameSinkId1));
 
   support.reset();
-  EXPECT_FALSE(FrameSinkIdExists(support->frame_sink_id()));
+  EXPECT_FALSE(FrameSinkIdExists(kFrameSinkId1));
 }
 
 }  // namespace test