CC Animations: Establish AnimationHost, AnimationTimeline and AnimationPlayer

cc/animation/animation_id_provider.cc

Index: cc/animation/animation_id_provider.cc
diff --git a/cc/animation/animation_id_provider.cc b/cc/animation/animation_id_provider.cc
index caefdb8fee588a5ae3f792861547e806b05604a2..445cef175af64f75b1509cc19c646e23d87b2f93 100644
--- a/cc/animation/animation_id_provider.cc
+++ b/cc/animation/animation_id_provider.cc
@@ -9,6 +9,7 @@ namespace cc {
 
 base::StaticAtomicSequenceNumber g_next_animation_id;
 base::StaticAtomicSequenceNumber g_next_group_id;
+base::StaticAtomicSequenceNumber g_next_player_id;
 
 int AnimationIdProvider::NextAnimationId() {
   // Animation IDs start from 1.
@@ -20,4 +21,9 @@ int AnimationIdProvider::NextGroupId() {
   return g_next_group_id.GetNext() + 1;
 }
 
+int AnimationIdProvider::NextPlayerId() {
+  // Animation player IDs start from 1.
+  return g_next_player_id.GetNext() + 1;
+}
+
 }  // namespace cc