CC Animations: Make LayerAnimationController creation optional

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 56b8c739e4f24004b59bf8a138f3cd3606cb7bf9..c605e0dc9e1ec5da2c69f9ede347e6f103df8066 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -34,6 +34,8 @@ namespace cc {
 
 base::StaticAtomicSequenceNumber g_next_layer_id;
 
+bool g_compositor_animation_timelines_enabled = false;
+
 scoped_refptr<Layer> Layer::Create() {
   return make_scoped_refptr(new Layer());
 }
@@ -83,9 +85,11 @@ Layer::Layer()
       raster_scale_(0.f),
       client_(nullptr),
       frame_timing_requests_dirty_(false) {
-  layer_animation_controller_ = LayerAnimationController::Create(layer_id_);
-  layer_animation_controller_->AddValueObserver(this);
-  layer_animation_controller_->set_value_provider(this);
+  if (!g_compositor_animation_timelines_enabled) {
+    layer_animation_controller_ = LayerAnimationController::Create(layer_id_);
+    layer_animation_controller_->AddValueObserver(this);
+    layer_animation_controller_->set_value_provider(this);
+  }
 }
 
 Layer::~Layer() {
@@ -96,8 +100,10 @@ Layer::~Layer() {
   // reference to us.
   DCHECK(!layer_tree_host());
 
-  layer_animation_controller_->RemoveValueObserver(this);
-  layer_animation_controller_->remove_value_provider(this);
+  if (layer_animation_controller_) {
+    layer_animation_controller_->RemoveValueObserver(this);
+    layer_animation_controller_->remove_value_provider(this);
+  }
 
   RemoveFromScrollTree();
   RemoveFromClipTree();
@@ -136,9 +142,7 @@ void Layer::SetLayerTreeHost(LayerTreeHost* host) {
     replica_layer_->SetLayerTreeHost(host);
 
   if (host) {
-    layer_animation_controller_->SetAnimationRegistrar(
-        host->animation_registrar());
-
+    RegisterForAnimations(host->animation_registrar(), host->settings());

[danakj, 2015/05/08 18:21:40]

if (layer_animation_controller_)?

[loyso (OOO), 2015/05/11 06:59:42]

Done in RegisterForAnimations.

     if (host->settings().layer_transforms_should_scale_layer_contents)
       reset_raster_scale_to_unknown();
   }
@@ -1349,7 +1353,13 @@ bool Layer::IsActive() const {
   return true;
 }
 
+// static
+void Layer::SetCompositorAnimationTimelinesEnabled(bool enabled) {
+  g_compositor_animation_timelines_enabled = enabled;
+}
+
 bool Layer::AddAnimation(scoped_ptr <Animation> animation) {
+  DCHECK(layer_animation_controller_);
   if (!layer_animation_controller_->animation_registrar())
     return false;
 
@@ -1394,13 +1404,20 @@ bool Layer::HasActiveAnimation() const {
   return layer_animation_controller_->HasActiveAnimation();
 }
 
+void Layer::RegisterForAnimations(AnimationRegistrar* registrar,
+                                  const LayerTreeSettings& settings) {

[danakj, 2015/05/08 18:21:40]

why are settings coming here but not being used?

[loyso (OOO), 2015/05/11 06:59:43]

Sorry, the CL was in inconsistent state (while prototyping possible approaches).
I was going to use it in the next-after-next CL
https://codereview.chromium.org/1010663002/patch/160001/170005

+  layer_animation_controller_->SetAnimationRegistrar(registrar);
+}
+
 void Layer::AddLayerAnimationEventObserver(
     LayerAnimationEventObserver* animation_observer) {
+  DCHECK(layer_animation_controller_);
   layer_animation_controller_->AddEventObserver(animation_observer);
 }
 
 void Layer::RemoveLayerAnimationEventObserver(
     LayerAnimationEventObserver* animation_observer) {
+  DCHECK(layer_animation_controller_);
   layer_animation_controller_->RemoveEventObserver(animation_observer);
 }