Revert "Shouldn't access LayerTreeTest::layer_tree_host on impl thread"

cc/trees/layer_tree_host_unittest_animation.cc

 // Copyright 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 "cc/trees/layer_tree_host.h"
 
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/animation/timing_function.h"
 #include "cc/layers/layer.h"
@@ skipping 273 matching lines @@
 
   virtual void AfterTest() OVERRIDE {}
 
  private:
   int num_animates_;
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(
     LayerTreeHostAnimationTestTickAnimationWhileBackgrounded);
 
+// Ensures that animations continue to be ticked when we are backgrounded.
 class LayerTreeHostAnimationTestAddAnimationWithTimingFunction
     : public LayerTreeHostAnimationTest {
  public:
   LayerTreeHostAnimationTestAddAnimationWithTimingFunction() {}
 
   virtual void SetupTree() OVERRIDE {
     LayerTreeHostAnimationTest::SetupTree();
     content_ = FakeContentLayer::Create(&client_);
     content_->SetBounds(gfx::Size(4, 4));
-    content_->set_layer_animation_delegate(this);
     layer_tree_host()->root_layer()->AddChild(content_);
   }
 
   virtual void BeginTest() OVERRIDE {
     PostAddAnimationToMainThread(content_);
   }
 
-  virtual void notifyAnimationStarted(double wallClockTime) OVERRIDE {
+  virtual void AnimateLayers(
+      LayerTreeHostImpl* host_impl,
+      base::TimeTicks monotonic_time) OVERRIDE {
     LayerAnimationController* controller =
         layer_tree_host()->root_layer()->children()[0]->
         layer_animation_controller();
     Animation* animation =
         controller->GetAnimation(Animation::Opacity);
+    if (!animation)
+      return;
+
     const FloatAnimationCurve* curve =
         animation->curve()->ToFloatAnimationCurve();
     float start_opacity = curve->GetValue(0.0);
     float end_opacity = curve->GetValue(curve->Duration());
     float linearly_interpolated_opacity =
         0.25f * end_opacity + 0.75f * start_opacity;
     double time = curve->Duration() * 0.25;
     // If the linear timing function associated with this animation was not
     // picked up, then the linearly interpolated opacity would be different
     // because of the default ease timing function.
     EXPECT_FLOAT_EQ(linearly_interpolated_opacity, curve->GetValue(time));
 
+    LayerAnimationController* controller_impl =
+        host_impl->active_tree()->root_layer()->children()[0]->
+        layer_animation_controller();
+    Animation* animation_impl =
+        controller_impl->GetAnimation(Animation::Opacity);
+
     controller->RemoveAnimation(animation->id());
-
+    controller_impl->RemoveAnimation(animation_impl->id());
     EndTest();
   }
 
   virtual void AfterTest() OVERRIDE {}
 
   FakeContentLayerClient client_;
   scoped_refptr<FakeContentLayer> content_;
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(
@@ skipping 451 matching lines @@
   int finished_times_;
   FakeContentLayerClient client_;
   scoped_refptr<FakeContentLayer> content_;
 };
 
 MULTI_THREAD_TEST_F(
     LayerTreeHostAnimationTestCheckerboardDoesntStartAnimations);
 
 }  // namespace
 }  // namespace cc