Disable flaky test LayerTreeHostTestCompositeAndReadbackDuringForcedDraw

According to
http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Chromium&testType=cc_unittests&tests=LayerTreeHostTestCompositeAndReadbackDuringForcedDraw.RunMultiThread_DirectRenderer_MainThreadPaint,
the test
LayerTreeHostTestCompositeAndReadbackDuringForcedDraw.RunMultiThread_DirectRenderer_MainThreadPaint
has failed 5 times out of 20 attempts on 9/9/2013. Disabling the test and
filing http://crbug.com/287893.

BUG=287893

Review URL: https://chromiumcodereview.appspot.com/23578016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222081 0039d316-1c4b-4281-b951-d872f2087c98

cc/trees/layer_tree_host_unittest.cc

@@ -545,7 +545,8 @@ class LayerTreeHostTestCompositeAndReadbackDuringForcedDraw
   virtual void AfterTest() OVERRIDE {}
 };
 
-MULTI_THREAD_TEST_F(LayerTreeHostTestCompositeAndReadbackDuringForcedDraw);
+// Flaky test. See http://crbug.com/287893.
+// MULTI_THREAD_TEST_F(LayerTreeHostTestCompositeAndReadbackDuringForcedDraw);
 
 class LayerTreeHostTestCompositeAndReadbackAfterForcedDraw
     : public LayerTreeHostTest {