CC Animation: Activate/deactivate ElementAnimations on Layer addition/removal.

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 <stdint.h>
 
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/animation_host.h"
@@ skipping 1232 matching lines @@
         EXPECT_FALSE(
             player_->element_animations()->has_element_in_pending_list());
         EXPECT_TRUE(layer_tree_host()->animation_host()->NeedsAnimateLayers());
         break;
       case 1:
         layer_->RemoveFromParent();
         EXPECT_FALSE(
             player_->element_animations()->has_element_in_active_list());
         EXPECT_FALSE(
             player_->element_animations()->has_element_in_pending_list());
-        EXPECT_TRUE(layer_tree_host()->animation_host()->NeedsAnimateLayers());
+        EXPECT_FALSE(layer_tree_host()->animation_host()->NeedsAnimateLayers());
         break;
       case 2:
         layer_tree_host()->root_layer()->AddChild(layer_);
         EXPECT_TRUE(
             player_->element_animations()->has_element_in_active_list());
         EXPECT_FALSE(
             player_->element_animations()->has_element_in_pending_list());
         EXPECT_TRUE(layer_tree_host()->animation_host()->NeedsAnimateLayers());
         break;
     }
   }
 
   void DidActivateTreeOnThread(LayerTreeHostImpl* host_impl) override {
     scoped_refptr<AnimationTimeline> timeline_impl =
         host_impl->animation_host()->GetTimelineById(timeline_id_);
     scoped_refptr<AnimationPlayer> player_impl =
         timeline_impl->GetPlayerById(player_id_);
 
     switch (host_impl->active_tree()->source_frame_number()) {
       case 0:
         EXPECT_TRUE(
             player_impl->element_animations()->has_element_in_active_list());
         EXPECT_TRUE(host_impl->animation_host()->NeedsAnimateLayers());
         break;
       case 1:
         EXPECT_FALSE(
             player_impl->element_animations()->has_element_in_active_list());
-        EXPECT_TRUE(host_impl->animation_host()->NeedsAnimateLayers());
+        EXPECT_FALSE(host_impl->animation_host()->NeedsAnimateLayers());
         break;
       case 2:
         EXPECT_TRUE(
             player_impl->element_animations()->has_element_in_active_list());
         EXPECT_TRUE(host_impl->animation_host()->NeedsAnimateLayers());
         EndTest();
         break;
     }
   }
 
@@ skipping 479 matching lines @@
  private:
   scoped_refptr<Layer> layer_;
   FakeContentLayerClient client_;
 };
 
 MULTI_THREAD_TEST_F(
     LayerTreeHostAnimationTestRebuildPropertyTreesOnAnimationSetNeedsCommit);
 
 }  // namespace
 }  // namespace cc