cc: ReadyToDraw notifications.

cc/resources/tile_manager.cc

Index: cc/resources/tile_manager.cc
diff --git a/cc/resources/tile_manager.cc b/cc/resources/tile_manager.cc
index 7fa2e3ee07bc6ed4f4b1e7170288d1bf45a80800..46824f303b0b42d8451af6e481d424b38fd4bc88 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -243,7 +243,10 @@ TileManager::TileManager(
       ready_to_activate_check_notifier_(
           task_runner_.get(),
           base::Bind(&TileManager::CheckIfReadyToActivate,
-                     base::Unretained(this))) {
+                     base::Unretained(this))),
+      ready_to_draw_check_notifier_(task_runner_.get(),
+                                    base::Bind(&TileManager::CheckIfReadyToDraw,
+                                               base::Unretained(this))) {
   rasterizer_->SetClient(this);
 }
 
@@ -385,6 +388,15 @@ void TileManager::DidFinishRunningTasks(TaskSet task_set) {
     return;
   }
 
+  if (task_set == REQUIRED_FOR_DRAW) {

[brianderson, 2014/10/24 01:34:04]

Can a task_set be both required for draw and required for activation? How does
this make sure we get both notifications if the pending tree has no new tiles
compared to the active tree?

[ernstm, 2014/10/24 04:54:20]

We get separate DidFinishRunningTasks notifications for each set that finishes. 
They are sent when all tasks in a set finished. If a set is empty (e.g. no tiles
required for activation), we still get a notification for it.

+    TRACE_EVENT1("cc",
+                 "TileManager::DidFinishRunningTasks",
+                 "task_set",
+                 "REQUIRED_FOR_DRAW");
+    ready_to_draw_check_notifier_.Schedule();
+    return;
+  }
+
   if (task_set == REQUIRED_FOR_ACTIVATION) {
     TRACE_EVENT1("cc",
                  "TileManager::DidFinishRunningTasks",
@@ -688,6 +700,8 @@ void TileManager::ScheduleTasks(
     TaskSetCollection task_sets;
     if (tile->required_for_activation())
       task_sets.set(REQUIRED_FOR_ACTIVATION);
+    if (tile->required_for_draw())
+      task_sets.set(REQUIRED_FOR_DRAW);
     task_sets.set(ALL);
     raster_queue_.items.push_back(
         RasterTaskQueue::Item(mts.raster_task.get(), task_sets));
@@ -867,6 +881,19 @@ bool TileManager::IsReadyToActivate() const {
   return true;
 }
 
+bool TileManager::IsReadyToDraw() const {
+  const std::vector<PictureLayerImpl*>& layers = client_->GetPictureLayers();
+
+  for (std::vector<PictureLayerImpl*>::const_iterator it = layers.begin();
+       it != layers.end();
+       ++it) {
+    if (!(*it)->AllTilesRequiredForDrawAreReadyToDraw())
+      return false;
+  }
+
+  return true;
+}
+
 void TileManager::CheckIfReadyToActivate() {
   TRACE_EVENT0("cc", "TileManager::CheckIfReadyToActivate");
 
@@ -877,6 +904,16 @@ void TileManager::CheckIfReadyToActivate() {
     client_->NotifyReadyToActivate();
 }
 
+void TileManager::CheckIfReadyToDraw() {
+  TRACE_EVENT0("cc", "TileManager::CheckIfReadyToDraw");
+
+  rasterizer_->CheckForCompletedTasks();
+  did_check_for_completed_tasks_since_last_schedule_tasks_ = true;
+
+  if (IsReadyToDraw())
+    client_->NotifyReadyToDraw();
+}
+
 TileManager::MemoryUsage::MemoryUsage() : memory_bytes_(0), resource_count_(0) {
 }