CC Animations: Fix AnimationHost mode integration with Property Trees.

cc/animation/animation_host.cc

Index: cc/animation/animation_host.cc
diff --git a/cc/animation/animation_host.cc b/cc/animation/animation_host.cc
index a9515be20aae6b20ab150c703853e27c5e70f649..5d8352f7d3b6e1011cd237d032247a11f7aba4fc 100644
--- a/cc/animation/animation_host.cc
+++ b/cc/animation/animation_host.cc
@@ -244,6 +244,11 @@ void AnimationHost::SetNeedsCommit() {
   mutator_host_client_->SetMutatorsNeedCommit();
 }
 
+void AnimationHost::SetNeedsRebuildPropertyTrees() {
+  DCHECK(mutator_host_client_);
+  mutator_host_client_->SetMutatorsNeedRebuildPropertyTrees();
+}
+
 void AnimationHost::PushPropertiesTo(AnimationHost* host_impl) {
   PushTimelinesToImplThread(host_impl);
   RemoveTimelinesFromImplThread(host_impl);