cc: Control activation from the Scheduler

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 9f664fcc0ee40385784ff1cf74c61cc32fcf5371..172273a99c7adbd054699955d7e45198fbd6dae4 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -254,7 +254,10 @@ void LayerTreeHostImpl::CommitComplete() {
     pending_tree_->set_needs_update_draw_properties();
     pending_tree_->UpdateDrawProperties();
     // Start working on newly created tiles immediately if needed.
-    ManageTiles();
+    if (!manage_tiles_needed_)
+      client_->NotifyReadyToActivate();
+    else
+      ManageTiles();
   } else {
     active_tree_->set_needs_update_draw_properties();
   }
@@ -1085,10 +1088,7 @@ void LayerTreeHostImpl::DidInitializeVisibleTile() {
 }
 
 void LayerTreeHostImpl::NotifyReadyToActivate() {
-  if (pending_tree_) {
-    need_to_update_visible_tiles_before_draw_ = true;
-    ActivatePendingTree();
-  }
+  client_->NotifyReadyToActivate();
 }
 
 bool LayerTreeHostImpl::ShouldClearRootRenderPass() const {
@@ -1476,6 +1476,8 @@ void LayerTreeHostImpl::ActivatePendingTree() {
   CHECK(pending_tree_);
   TRACE_EVENT_ASYNC_END0("cc", "PendingTree", pending_tree_.get());
 
+  need_to_update_visible_tiles_before_draw_ = true;
+
   active_tree_->SetRootLayerScrollOffsetDelegate(NULL);
   active_tree_->PushPersistedState(pending_tree_.get());
   if (pending_tree_->needs_full_tree_sync()) {
@@ -1504,6 +1506,10 @@ void LayerTreeHostImpl::ActivatePendingTree() {
       root_layer_scroll_offset_delegate_);
   active_tree_->DidBecomeActive();
 
+  client_->DidActivatePendingTree();
+  if (!tree_activation_callback_.is_null())
+    tree_activation_callback_.Run();
+
   // Reduce wasted memory now that unlinked resources are guaranteed not
   // to be used.
   client_->ReduceWastedContentsTextureMemoryOnImplThread();
@@ -1520,10 +1526,6 @@ void LayerTreeHostImpl::ActivatePendingTree() {
         stats.main_stats.paint_time + stats.main_stats.record_time +
             stats.impl_stats.rasterize_time_for_now_bins_on_pending_tree);
   }
-
-  client_->DidActivatePendingTree();
-  if (!tree_activation_callback_.is_null())
-    tree_activation_callback_.Run();
 }
 
 void LayerTreeHostImpl::SetVisible(bool visible) {