Add support for inverse transform animations.

ui/compositor/layer_animation_element_unittest.cc

 // Copyright (c) 2012 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 "ui/compositor/layer_animation_element.h"
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/compositor/layer_animation_delegate.h"
 #include "ui/compositor/test/test_layer_animation_delegate.h"
 #include "ui/compositor/test/test_utils.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
 
 namespace ui {
 
 namespace {
 
 // Check that the transformation element progresses the delegate as expected and
 // that the element can be reused after it completes.
 TEST(LayerAnimationElementTest, TransformElement) {
   TestLayerAnimationDelegate delegate;
-  gfx::Transform start_transform, target_transform, middle_transform;
+  gfx::Transform start_transform, target_transform;
   start_transform.Rotate(-30.0);
   target_transform.Rotate(30.0);
   base::TimeTicks start_time;
   base::TimeTicks effective_start_time;
   base::TimeDelta delta = base::TimeDelta::FromSeconds(1);
 
   scoped_ptr<LayerAnimationElement> element(
       LayerAnimationElement::CreateTransformElement(target_transform, delta));
   element->set_animation_group_id(1);
 
@@ skipping 328 matching lines @@
   element->Abort(&delegate);
   target_transform.Blend(start_transform,
                          Tween::CalculateValue(tween_type, 0.5));
   CheckApproximatelyEqual(target_transform,
                           delegate.GetTransformForAnimation());
 }
 
 } // namespace
 
 } // namespace ui