CC Animations: Fix the case when main-thread player changes layer_id.

cc/animation/animation_player_unittest.cc

 // 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.
 
 #include "cc/animation/animation_player.h"
 
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/animation_registrar.h"
@@ skipping 314 matching lines @@
 
   player_->PauseAnimation(animation_id, 1.);
   EXPECT_TRUE(client_.mutators_need_commit());
   client_.set_mutators_need_commit(false);
 
   player_->RemoveAnimation(animation_id);
   EXPECT_TRUE(client_.mutators_need_commit());
   client_.set_mutators_need_commit(false);
 }
 
+// If main-thread player switches to another layer within one frame then
+// impl-thread player must be switched as well.
+TEST_F(AnimationPlayerTest, SwitchToLayer) {
+  host_->AddAnimationTimeline(timeline_);
+  timeline_->AttachPlayer(player_);
+  player_->AttachLayer(layer_id_);
+
+  host_->PushPropertiesTo(host_impl_);
+
+  GetImplTimelineAndPlayerByID();
+
+  EXPECT_EQ(player_, GetPlayerForLayerId(layer_id_));
+  EXPECT_TRUE(player_->element_animations());
+  EXPECT_EQ(player_->layer_id(), layer_id_);
+
+  EXPECT_EQ(player_impl_, GetImplPlayerForLayerId(layer_id_));
+  EXPECT_TRUE(player_impl_->element_animations());
+  EXPECT_EQ(player_impl_->layer_id(), layer_id_);
+
+  const int new_layer_id = NextTestLayerId();
+  player_->DetachLayer();
+  player_->AttachLayer(new_layer_id);
+
+  EXPECT_EQ(player_, GetPlayerForLayerId(new_layer_id));
+  EXPECT_TRUE(player_->element_animations());
+  EXPECT_EQ(player_->layer_id(), new_layer_id);
+
+  host_->PushPropertiesTo(host_impl_);
+
+  EXPECT_EQ(player_impl_, GetImplPlayerForLayerId(new_layer_id));
+  EXPECT_TRUE(player_impl_->element_animations());
+  EXPECT_EQ(player_impl_->layer_id(), new_layer_id);
+}
+
 }  // namespace
 }  // namespace cc