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

cc/test/animation_timelines_test_common.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/test/animation_timelines_test_common.h"
 
 #include "cc/animation/animation_events.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/animation_player.h"
 #include "cc/animation/animation_registrar.h"
@@ skipping 179 matching lines @@
   finished_ = true;
 }
 
 AnimationTimelinesTest::AnimationTimelinesTest()
     : client_(ThreadInstance::MAIN),
       client_impl_(ThreadInstance::IMPL),
       host_(nullptr),
       host_impl_(nullptr),
       timeline_id_(AnimationIdProvider::NextTimelineId()),
       player_id_(AnimationIdProvider::NextPlayerId()),
-      layer_id_(1) {
+      next_test_layer_id_(0) {
   host_ = client_.host();
   host_impl_ = client_impl_.host();
+
+  layer_id_ = NextTestLayerId();
 }
 
 AnimationTimelinesTest::~AnimationTimelinesTest() {
 }
 
 void AnimationTimelinesTest::SetUp() {
   timeline_ = AnimationTimeline::Create(timeline_id_);
   player_ = AnimationPlayer::Create(player_id_);
 }
 
@@ skipping 38 matching lines @@
                             : nullptr;
 }
 
 AnimationPlayer* AnimationTimelinesTest::GetImplPlayerForLayerId(int layer_id) {
   const ElementAnimations* element_animations =
       host_impl_->GetElementAnimationsForLayerId(layer_id);
   return element_animations ? element_animations->players_list().head()->value()
                             : nullptr;
 }
 
+int AnimationTimelinesTest::NextTestLayerId() {
+  next_test_layer_id_++;
+  return next_test_layer_id_;
+}
+
 }  // namespace cc