CC: Add a scheduled action for ManageTiles

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 816383a6eb136e180b8874cce0576b24b1852120..32f9a2cd3225dfa9c177062bf33eee555c0f5491 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -174,7 +174,7 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       did_lock_scrolling_layer_(false),
       should_bubble_scrolls_(false),
       wheel_scrolling_(false),
-      manage_tiles_needed_(false),
+      tile_priorities_dirty_(false),
       root_layer_scroll_offset_delegate_(NULL),
       settings_(settings),
       visible_(true),
@@ -255,7 +255,7 @@ void LayerTreeHostImpl::CommitComplete() {
     pending_tree_->set_needs_update_draw_properties();
     pending_tree_->UpdateDrawProperties();
     // Start working on newly created tiles immediately if needed.
-    if (!tile_manager_ || !manage_tiles_needed_)
+    if (!tile_manager_ || !tile_priorities_dirty_)
       NotifyReadyToActivate();
     else
       ManageTiles();

[brianderson, 2013/09/11 17:10:30]

Will this ManageTiles() be a redundant call now that the Scheduler initiates
ManageTiles?  It was very confusing and error prone when both the Scheduler and
LTHI were activating the pending tree. If the Scheduler is going to be calling
ManageTiles, I think it would be a good idea to make it the only class that
initiates them.

[epennerAtGoogle, 2013/09/11 18:43:00]

This isn't redundant unless we replicate this behavior in the Scheduler.
Currently I don't do that. I do think it should move to the Scheduler but I
don't know if that should be in this first patch.

In terms of replicating it, I _think_ we could get away doing only this
ManageTiles (somewhere in the scheduler) and skipping any other ManageTiles
within the same frame... But I'm a bit hesitant to conclude that's always okay.

@@ -327,12 +327,12 @@ void LayerTreeHostImpl::Animate(base::TimeTicks monotonic_time,
 void LayerTreeHostImpl::ManageTiles() {
   if (!tile_manager_)
     return;
-  if (!manage_tiles_needed_)
+  if (!tile_priorities_dirty_)
     return;
   if (!device_viewport_valid_for_tile_management_)
     return;
 
-  manage_tiles_needed_ = false;
+  tile_priorities_dirty_ = false;
   tile_manager_->ManageTiles();
 
   size_t memory_required_bytes;
@@ -1108,8 +1108,15 @@ void LayerTreeHostImpl::UpdateTileManagerMemoryPolicy(
           policy.priority_cutoff_when_visible :
           policy.priority_cutoff_when_not_visible);
   new_state.num_resources_limit = policy.num_resources_limit;
+
+  WillModifyTilePriorities();
   tile_manager_->SetGlobalState(new_state);
-  manage_tiles_needed_ = true;
+}
+
+void LayerTreeHostImpl::WillModifyTilePriorities() {
+  // Mark priorities as dirty and schedule a ManageTiles().
+  tile_priorities_dirty_ = true;
+  client_->SetNeedsManageTilesOnImplThread();
 }
 
 void LayerTreeHostImpl::DidInitializeVisibleTile() {
@@ -2509,8 +2516,9 @@ void LayerTreeHostImpl::SetTreePriority(TreePriority priority) {
     return;
 
   new_state.tree_priority = priority;
+
+  WillModifyTilePriorities();
   tile_manager_->SetGlobalState(new_state);
-  manage_tiles_needed_ = true;
 }
 
 void LayerTreeHostImpl::ResetCurrentFrameTimeForNextFrame() {