Moving background animation ticking from LayerTreeHostImpl into the Scheduler.

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index 37830f601dd0ce1351ecddc55fb0bd6b59b7dd1c..65e8dd27a35de390d404d951d5b701fc56dc5224 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -176,18 +176,9 @@ void ThreadProxy::SetVisibleOnImplThread(CompletionEvent* completion,
   TRACE_EVENT0("cc", "ThreadProxy::SetVisibleOnImplThread");
   impl().layer_tree_host_impl->SetVisible(visible);
   impl().scheduler->SetVisible(visible);
-  UpdateBackgroundAnimateTicking();
   completion->Signal();
 }
 
-void ThreadProxy::UpdateBackgroundAnimateTicking() {
-  bool should_background_tick =
-      !impl().scheduler->WillDrawIfNeeded() &&
-      impl().layer_tree_host_impl->active_tree()->root_layer();
-  impl().layer_tree_host_impl->UpdateBackgroundAnimateTicking(
-      should_background_tick);
-}
-
 void ThreadProxy::DidLoseOutputSurface() {
   TRACE_EVENT0("cc", "ThreadProxy::DidLoseOutputSurface");
   DCHECK(IsMainThread());
@@ -358,7 +349,6 @@ void ThreadProxy::OnCanDrawStateChanged(bool can_draw) {
       "cc", "ThreadProxy::OnCanDrawStateChanged", "can_draw", can_draw);
   DCHECK(IsImplThread());
   impl().scheduler->SetCanDraw(can_draw);
-  UpdateBackgroundAnimateTicking();
 }
 
 void ThreadProxy::NotifyReadyToActivate() {
@@ -927,9 +917,22 @@ void ThreadProxy::ScheduledActionAnimate() {
   TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionAnimate");
   DCHECK(IsImplThread());
 
+  // Don't animate if there is no root layer.
+  // TODO(mithro): Both Animate and UpdateAnimationState already have a
+  // "!active_tree_->root_layer()" check?
+  if (!impl().layer_tree_host_impl->active_tree()->root_layer()) {
+    return;
+  }
+
   impl().animation_time =
       impl().layer_tree_host_impl->CurrentBeginFrameArgs().frame_time;
   impl().layer_tree_host_impl->Animate(impl().animation_time);
+
+  // If animations are not visible, update the state now as
+  // ScheduledActionDrawAndSwapIfPossible will never be called.
+  if (!impl().layer_tree_host_impl->AnimationsAreVisible()) {
+    impl().layer_tree_host_impl->UpdateAnimationState(true);
+  }
 }
 
 void ThreadProxy::ScheduledActionCommit() {
@@ -973,8 +976,6 @@ void ThreadProxy::ScheduledActionCommit() {
 
   SetInputThrottledUntilCommitOnImplThread(false);
 
-  UpdateBackgroundAnimateTicking();
-
   impl().next_frame_is_newly_committed_frame = true;
 
   impl().timing_history.DidCommit();
@@ -1352,8 +1353,6 @@ void ThreadProxy::DidActivateSyncTree() {
     impl().completion_event_for_commit_held_on_tree_activation = NULL;
   }
 
-  UpdateBackgroundAnimateTicking();
-
   impl().timing_history.DidActivateSyncTree();
 }