[Sketch] CC Animations: Torpedo the old intrusive animation system.

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 06fb427d984ab258cbd59ecacb7f9671b1a8e5d2..f34a7075629d211e7e7dcbed502206ccd3e429e0 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -138,9 +138,6 @@ Compositor::Compositor(gfx::AcceleratedWidget widget,
   // raster threads.
   settings.gather_pixel_refs = false;
 
-  settings.use_compositor_animation_timelines =
-      command_line->HasSwitch(switches::kUIEnableCompositorAnimationTimelines);
-
   base::TimeTicks before_create = base::TimeTicks::Now();
   host_ = cc::LayerTreeHost::CreateSingleThreaded(
       this, this, context_factory_->GetSharedBitmapManager(),
@@ -149,11 +146,10 @@ Compositor::Compositor(gfx::AcceleratedWidget widget,
   UMA_HISTOGRAM_TIMES("GPU.CreateBrowserCompositor",
                       base::TimeTicks::Now() - before_create);
 
-  if (settings.use_compositor_animation_timelines) {
-    animation_timeline_ = cc::AnimationTimeline::Create(
-        cc::AnimationIdProvider::NextTimelineId());
-    host_->animation_host()->AddAnimationTimeline(animation_timeline_.get());
-  }
+  animation_timeline_ =
+      cc::AnimationTimeline::Create(cc::AnimationIdProvider::NextTimelineId());
+  host_->animation_host()->AddAnimationTimeline(animation_timeline_.get());
+
   host_->SetRootLayer(root_web_layer_);
   host_->set_surface_id_namespace(surface_id_allocator_->id_namespace());
   host_->SetLayerTreeHostClientReady();
@@ -173,8 +169,7 @@ Compositor::~Compositor() {
   if (root_layer_)
     root_layer_->ResetCompositor();
 
-  if (animation_timeline_)
-    host_->animation_host()->RemoveAnimationTimeline(animation_timeline_.get());
+  host_->animation_host()->RemoveAnimationTimeline(animation_timeline_.get());
 
   // Stop all outstanding draws before telling the ContextFactory to tear
   // down any contexts that the |host_| may rely upon.
@@ -206,7 +201,6 @@ void Compositor::SetRootLayer(Layer* root_layer) {
 }
 
 cc::AnimationTimeline* Compositor::GetAnimationTimeline() const {
-  DCHECK(animation_timeline_);
   return animation_timeline_.get();
 }