Fix potential NULL pointer in LayerTreeHostImpl

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 5678 matching lines @@
   output_surface->set_forced_draw_to_software_device(true);
   EXPECT_TRUE(output_surface->ForcedDrawToSoftwareDevice());
 
   EXPECT_EQ(0, software_device->frames_began_);
   EXPECT_EQ(0, software_device->frames_ended_);
 
   DrawFrame();
 
   EXPECT_EQ(1, software_device->frames_began_);
   EXPECT_EQ(1, software_device->frames_ended_);
+
+  // Call other API methods that are likely to hit NULL pointer in this mode.
+  EXPECT_TRUE(host_impl_->AsValue());
+  EXPECT_TRUE(host_impl_->ActivationStateAsValue());
 }
 
 }  // namespace
 }  // namespace cc