cc: Make OutputSurface entirely live on one thread in tests.

cc/test/test_hooks.h

 // Copyright 2015 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.
 
 #ifndef CC_TEST_TEST_HOOKS_H_
 #define CC_TEST_TEST_HOOKS_H_
 
 #include "base/macros.h"
 #include "cc/animation/animation_delegate.h"
 #include "cc/trees/layer_tree_host.h"
@@ skipping 95 matching lines @@
                                int group) override {}
   void NotifyAnimationAborted(base::TimeTicks monotonic_time,
                               TargetProperty::Type target_property,
                               int group) override {}
   void NotifyAnimationTakeover(base::TimeTicks monotonic_time,
                                TargetProperty::Type target_property,
                                double animation_start_time,
                                std::unique_ptr<AnimationCurve> curve) override {
   }
 
+  // OutputSurface indirections to the LayerTreeTest, that can be further
+  // overridden.
   virtual void RequestNewCompositorFrameSink() = 0;
+  virtual std::unique_ptr<OutputSurface> CreateDisplayOutputSurfaceOnThread(
+      scoped_refptr<ContextProvider> compositor_context_provider) = 0;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_TEST_HOOKS_H_