Harmonize LayerTreeHost/LayerTreeHostImpl synchronization steps

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 2057 matching lines @@
           pending_tree()->property_trees()->effect_tree.set_needs_update(true);
         }
       }
     }
   }
 }
 
 void LayerTreeHostImpl::ActivateSyncTree() {
   if (pending_tree_) {
     TRACE_EVENT_ASYNC_END0("cc", "PendingTree:waiting", pending_tree_.get());
+    active_tree_->lifecycle().AdvanceTo(LayerTreeLifecycle::kBeginningSync);
 
     DCHECK(pending_tree_duration_timer_);
     // Reset will call the destructor and log the timer histogram.
     pending_tree_duration_timer_.reset();
 
     // Process any requests in the UI resource queue.  The request queue is
     // given in LayerTreeHost::FinishCommitOnImplThread.  This must take place
     // before the swap.
     pending_tree_->ProcessUIResourceRequestQueue();
 
     if (pending_tree_->needs_full_tree_sync()) {
       TreeSynchronizer::SynchronizeTrees(pending_tree_.get(),
                                          active_tree_.get());
     }
 
-    // Property trees may store damage status. We preserve the active tree
-    // damage status by pushing the damage status from active tree property
-    // trees to pending tree property trees or by moving it onto the layers.
-    if (active_tree_->property_trees()->changed) {
-      if (pending_tree_->property_trees()->sequence_number ==
-          active_tree_->property_trees()->sequence_number)
-        active_tree_->property_trees()->PushChangeTrackingTo(
-            pending_tree_->property_trees());
-      else
-        active_tree_->MoveChangeTrackingToLayers();
-    }
+    PushScrollbarOpacitiesFromActiveToPending();
+    pending_tree_->PushPropertyTreesTo(active_tree_.get());
+    active_tree_->lifecycle().AdvanceTo(
+        LayerTreeLifecycle::kSyncedPropertyTrees);
+
     TreeSynchronizer::PushLayerProperties(pending_tree(), active_tree());
-
-    PushScrollbarOpacitiesFromActiveToPending();
+    active_tree_->lifecycle().AdvanceTo(
+        LayerTreeLifecycle::kSyncedLayerProperties);
 
     pending_tree_->PushPropertiesTo(active_tree_.get());
     if (!pending_tree_->LayerListIsEmpty())
       pending_tree_->property_trees()->ResetAllChangeTracking();
 
+    active_tree_->lifecycle().AdvanceTo(LayerTreeLifecycle::kNotSyncing);
+
     // Now that we've synced everything from the pending tree to the active
     // tree, rename the pending tree the recycle tree so we can reuse it on the
     // next sync.
     DCHECK(!recycle_tree_);
     pending_tree_.swap(recycle_tree_);
 
     // If we commit to the active tree directly, this is already done during
     // commit.
     ActivateAnimations();
 
@@ skipping 2211 matching lines @@
 
 void LayerTreeHostImpl::ShowScrollbarsForImplScroll(ElementId element_id) {
   if (!element_id)
     return;
   if (ScrollbarAnimationController* animation_controller =
           ScrollbarAnimationControllerForElementId(element_id))
     animation_controller->DidScrollUpdate();
 }
 
 }  // namespace cc