Disable flaky test LayerTreeHostCopyRequestTestMultipleRequests.GLRenderer_RunSingleThread

cc/trees/layer_tree_host_unittest_copyrequest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/test/fake_content_layer.h"
 #include "cc/test/fake_content_layer_client.h"
 #include "cc/test/fake_output_surface.h"
 #include "cc/test/layer_tree_test.h"
@@ skipping 100 matching lines @@
   }
 
   bool use_gl_renderer_;
   std::vector<gfx::Size> callbacks_;
   FakeContentLayerClient client_;
   scoped_refptr<FakeContentLayer> root;
   scoped_refptr<FakeContentLayer> child;
 };
 
 // Readback can't be done with a delegating renderer.
+// Disabled due to flake: http://crbug.com/448521
 TEST_F(LayerTreeHostCopyRequestTestMultipleRequests,
-       GLRenderer_RunSingleThread) {
+       DISABLED_GLRenderer_RunSingleThread) {
   use_gl_renderer_ = true;
   RunTest(false, false, false);
 }
 
 TEST_F(LayerTreeHostCopyRequestTestMultipleRequests,
        GLRenderer_RunMultiThread_MainThreadPainting) {
   use_gl_renderer_ = true;
   RunTest(true, false, false);
 }
 
@@ skipping 827 matching lines @@
   FakeContentLayerClient client_;
   scoped_refptr<FakeContentLayer> root_;
   scoped_refptr<FakeContentLayer> copy_layer_;
 };
 
 SINGLE_AND_MULTI_THREAD_DIRECT_RENDERER_TEST_F(
     LayerTreeHostCopyRequestTestShutdownBeforeCopy);
 
 }  // namespace
 }  // namespace cc