CC Animation: Erase LayerTreeSettings::accelerated_animation_enabled flag.

We use disable-threaded-animation command line switch for
testing purposes.

Now blink knows ahead of time, whether we support threaded animations.

See
RendererBlinkPlatformImpl::isThreadedAnimationEnabled()

BUG=575041
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1798503004

Cr-Commit-Position: refs/heads/master@{#381192}

6 files changed, 79 insertions, 191 deletions

diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 437ca4b..e669e27 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -197,10 +197,8 @@ LayerTreeHost::LayerTreeHost(InitParams* params, CompositorMode mode)
       next_surface_sequence_(1u) {
   DCHECK(task_graph_runner_);
 
-  if (settings_.accelerated_animation_enabled) {
-    animation_host_ = AnimationHost::Create(ThreadInstance::MAIN);
-    animation_host_->SetMutatorHostClient(this);
-  }
+  animation_host_ = AnimationHost::Create(ThreadInstance::MAIN);
+  animation_host_->SetMutatorHostClient(this);
 
   rendering_stats_instrumentation_->set_record_rendering_stats(
       debug_state_.RecordRenderingStats());
@@ -285,17 +283,14 @@ void LayerTreeHost::InitializeProxy(
 
   proxy_ = std::move(proxy);
   proxy_->Start(std::move(external_begin_frame_source));
-  if (settings_.accelerated_animation_enabled) {
-    animation_host_->SetSupportsScrollAnimations(
-        proxy_->SupportsImplScrolling());
-  }
+
+  animation_host_->SetSupportsScrollAnimations(proxy_->SupportsImplScrolling());
 }
 
 LayerTreeHost::~LayerTreeHost() {
   TRACE_EVENT0("cc", "LayerTreeHost::~LayerTreeHost");
 
-  if (animation_host_)
-    animation_host_->SetMutatorHostClient(nullptr);
+  animation_host_->SetMutatorHostClient(nullptr);
 
   if (root_layer_.get())
     root_layer_->SetLayerTreeHost(NULL);
@@ -473,11 +468,9 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
     TRACE_EVENT0("cc", "LayerTreeHost::PushProperties");
     TreeSynchronizer::PushProperties(root_layer(), sync_tree->root_layer());
 
-    if (animation_host_) {
-      TRACE_EVENT0("cc", "LayerTreeHost::AnimationHost::PushProperties");
-      DCHECK(host_impl->animation_host());
-      animation_host_->PushPropertiesTo(host_impl->animation_host());
-    }
+    TRACE_EVENT0("cc", "LayerTreeHost::AnimationHost::PushProperties");
+    DCHECK(host_impl->animation_host());
+    animation_host_->PushPropertiesTo(host_impl->animation_host());
   }
 
   // This must happen after synchronizing property trees and after push
@@ -1048,11 +1041,8 @@ void LayerTreeHost::UpdateTopControlsState(TopControlsState constraints,
 }
 
 void LayerTreeHost::AnimateLayers(base::TimeTicks monotonic_time) {
-  if (!settings_.accelerated_animation_enabled)
-    return;
+  scoped_ptr<AnimationEvents> events = animation_host_->CreateEvents();
 
-  scoped_ptr<AnimationEvents> events;
-  events = animation_host_->CreateEvents();
   if (animation_host_->AnimateLayers(monotonic_time))
     animation_host_->UpdateAnimationState(true, events.get());
 
@@ -1236,15 +1226,13 @@ void LayerTreeHost::RegisterLayer(Layer* layer) {
   DCHECK(!LayerById(layer->id()));
   DCHECK(!in_paint_layer_contents_);
   layer_id_map_[layer->id()] = layer;
-  if (animation_host_)
-    animation_host_->RegisterLayer(layer->id(), LayerTreeType::ACTIVE);
+  animation_host_->RegisterLayer(layer->id(), LayerTreeType::ACTIVE);
 }
 
 void LayerTreeHost::UnregisterLayer(Layer* layer) {
   DCHECK(LayerById(layer->id()));
   DCHECK(!in_paint_layer_contents_);
-  if (animation_host_)
-    animation_host_->UnregisterLayer(layer->id(), LayerTreeType::ACTIVE);
+  animation_host_->UnregisterLayer(layer->id(), LayerTreeType::ACTIVE);
   layer_id_map_.erase(layer->id());
 }
 
@@ -1311,103 +1299,76 @@ gfx::ScrollOffset LayerTreeHost::GetScrollOffsetForAnimation(
 
 bool LayerTreeHost::ScrollOffsetAnimationWasInterrupted(
     const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->ScrollOffsetAnimationWasInterrupted(layer->id())
-             : false;
+  return animation_host_->ScrollOffsetAnimationWasInterrupted(layer->id());
 }
 
 bool LayerTreeHost::IsAnimatingFilterProperty(const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->IsAnimatingFilterProperty(layer->id(),
-                                                          LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->IsAnimatingFilterProperty(layer->id(),
+                                                    LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::IsAnimatingOpacityProperty(const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->IsAnimatingOpacityProperty(
-                   layer->id(), LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->IsAnimatingOpacityProperty(layer->id(),
+                                                     LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::IsAnimatingTransformProperty(const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->IsAnimatingTransformProperty(
-                   layer->id(), LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->IsAnimatingTransformProperty(layer->id(),
+                                                       LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::HasPotentiallyRunningFilterAnimation(
     const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->HasPotentiallyRunningFilterAnimation(
-                   layer->id(), LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->HasPotentiallyRunningFilterAnimation(
+      layer->id(), LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::HasPotentiallyRunningOpacityAnimation(
     const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->HasPotentiallyRunningOpacityAnimation(
-                   layer->id(), LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->HasPotentiallyRunningOpacityAnimation(
+      layer->id(), LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::HasPotentiallyRunningTransformAnimation(
     const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->HasPotentiallyRunningTransformAnimation(
-                   layer->id(), LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->HasPotentiallyRunningTransformAnimation(
+      layer->id(), LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::HasOnlyTranslationTransforms(const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->HasOnlyTranslationTransforms(
-                   layer->id(), LayerTreeType::ACTIVE)
-             : false;
+  return animation_host_->HasOnlyTranslationTransforms(layer->id(),
+                                                       LayerTreeType::ACTIVE);
 }
 
 bool LayerTreeHost::MaximumTargetScale(const Layer* layer,
                                        float* max_scale) const {
-  return animation_host_
-             ? animation_host_->MaximumTargetScale(
-                   layer->id(), LayerTreeType::ACTIVE, max_scale)
-             : false;
+  return animation_host_->MaximumTargetScale(layer->id(), LayerTreeType::ACTIVE,
+                                             max_scale);
 }
 
 bool LayerTreeHost::AnimationStartScale(const Layer* layer,
                                         float* start_scale) const {
-  return animation_host_
-             ? animation_host_->AnimationStartScale(
-                   layer->id(), LayerTreeType::ACTIVE, start_scale)
-             : false;
+  return animation_host_->AnimationStartScale(
+      layer->id(), LayerTreeType::ACTIVE, start_scale);
 }
 
 bool LayerTreeHost::HasAnyAnimationTargetingProperty(
     const Layer* layer,
     TargetProperty::Type property) const {
-  return animation_host_
-             ? animation_host_->HasAnyAnimationTargetingProperty(layer->id(),
-                                                                 property)
-             : false;
+  return animation_host_->HasAnyAnimationTargetingProperty(layer->id(),
+                                                           property);
 }
 
 bool LayerTreeHost::AnimationsPreserveAxisAlignment(const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->AnimationsPreserveAxisAlignment(layer->id())
-             : true;
+  return animation_host_->AnimationsPreserveAxisAlignment(layer->id());
 }
 
 bool LayerTreeHost::HasAnyAnimation(const Layer* layer) const {
-  return animation_host_ ? animation_host_->HasAnyAnimation(layer->id())
-                         : false;
+  return animation_host_->HasAnyAnimation(layer->id());
 }
 
 bool LayerTreeHost::HasActiveAnimationForTesting(const Layer* layer) const {
-  return animation_host_
-             ? animation_host_->HasActiveAnimationForTesting(layer->id())
-             : false;
+  return animation_host_->HasActiveAnimationForTesting(layer->id());
 }
 
 bool LayerTreeHost::IsSingleThreaded() const {
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 0a9fdb3..5e21974 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -236,11 +236,9 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       requires_high_res_to_draw_(false),
       is_likely_to_require_a_draw_(false),
       frame_timing_tracker_(FrameTimingTracker::Create(this)) {
-  if (settings.accelerated_animation_enabled) {
-    animation_host_ = AnimationHost::Create(ThreadInstance::IMPL);
-    animation_host_->SetMutatorHostClient(this);
-    animation_host_->SetSupportsScrollAnimations(SupportsImplScrolling());
-  }
+  animation_host_ = AnimationHost::Create(ThreadInstance::IMPL);
+  animation_host_->SetMutatorHostClient(this);
+  animation_host_->SetSupportsScrollAnimations(SupportsImplScrolling());
 
   DCHECK(task_runner_provider_->IsImplThread());
   DidVisibilityChange(this, visible_);
@@ -289,10 +287,8 @@ LayerTreeHostImpl::~LayerTreeHostImpl() {
   pending_tree_ = nullptr;
   active_tree_ = nullptr;
 
-  if (animation_host_) {
-    animation_host_->ClearTimelines();
-    animation_host_->SetMutatorHostClient(nullptr);
-  }
+  animation_host_->ClearTimelines();
+  animation_host_->SetMutatorHostClient(nullptr);
 
   CleanUpTileManagerAndUIResources();
   renderer_ = nullptr;
@@ -3389,12 +3385,7 @@ bool LayerTreeHostImpl::AnimateScrollbars(base::TimeTicks monotonic_time) {
 }
 
 bool LayerTreeHostImpl::AnimateLayers(base::TimeTicks monotonic_time) {
-  if (!settings_.accelerated_animation_enabled)
-    return false;
-
-  bool animated = false;
-  if (animation_host_->AnimateLayers(monotonic_time))
-    animated = true;
+  const bool animated = animation_host_->AnimateLayers(monotonic_time);
 
   // TODO(crbug.com/551134): Only do this if the animations are on the active
   // tree, or if they are on the pending tree waiting for some future time to
@@ -3411,14 +3402,9 @@ bool LayerTreeHostImpl::AnimateLayers(base::TimeTicks monotonic_time) {
 }
 
 void LayerTreeHostImpl::UpdateAnimationState(bool start_ready_animations) {
-  if (!settings_.accelerated_animation_enabled)
-    return;
-
-  bool has_active_animations = false;
-  scoped_ptr<AnimationEvents> events;
+  scoped_ptr<AnimationEvents> events = animation_host_->CreateEvents();
 
-  events = animation_host_->CreateEvents();
-  has_active_animations = animation_host_->UpdateAnimationState(
+  const bool has_active_animations = animation_host_->UpdateAnimationState(
       start_ready_animations, events.get());
 
   if (!events->events_.empty())
@@ -3429,9 +3415,6 @@ void LayerTreeHostImpl::UpdateAnimationState(bool start_ready_animations) {
 }
 
 void LayerTreeHostImpl::ActivateAnimations() {
-  if (!settings_.accelerated_animation_enabled)
-    return;
-
   const bool activated = animation_host_->ActivateAnimations();
   if (activated) {
     // Activating an animation changes layer draw properties, such as
@@ -3849,9 +3832,7 @@ void LayerTreeHostImpl::TreeLayerTransformIsPotentiallyAnimatingChanged(
 
 bool LayerTreeHostImpl::AnimationsPreserveAxisAlignment(
     const LayerImpl* layer) const {
-  return animation_host_
-             ? animation_host_->AnimationsPreserveAxisAlignment(layer->id())
-             : true;
+  return animation_host_->AnimationsPreserveAxisAlignment(layer->id());
 }
 
 void LayerTreeHostImpl::SetLayerFilterMutated(int layer_id,
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index f5702ed..dae2e2c 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -981,18 +981,16 @@ bool LayerTreeImpl::LayerNeedsPushPropertiesForTesting(LayerImpl* layer) {
 void LayerTreeImpl::RegisterLayer(LayerImpl* layer) {
   DCHECK(!LayerById(layer->id()));
   layer_id_map_[layer->id()] = layer;
-  if (layer_tree_host_impl_->animation_host())
-    layer_tree_host_impl_->animation_host()->RegisterLayer(
-        layer->id(),
-        IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING);
+  layer_tree_host_impl_->animation_host()->RegisterLayer(
+      layer->id(),
+      IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING);
 }
 
 void LayerTreeImpl::UnregisterLayer(LayerImpl* layer) {
   DCHECK(LayerById(layer->id()));
-  if (layer_tree_host_impl_->animation_host())
-    layer_tree_host_impl_->animation_host()->UnregisterLayer(
-        layer->id(),
-        IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING);
+  layer_tree_host_impl_->animation_host()->UnregisterLayer(
+      layer->id(),
+      IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING);
   layer_id_map_.erase(layer->id());
 }
 
@@ -1887,28 +1885,22 @@ LayerTreeImpl::TakePendingPageScaleAnimation() {
 bool LayerTreeImpl::IsAnimatingFilterProperty(const LayerImpl* layer) const {
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->IsAnimatingFilterProperty(layer->id(), tree_type)
-             : false;
+  return layer_tree_host_impl_->animation_host()->IsAnimatingFilterProperty(
+      layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::IsAnimatingOpacityProperty(const LayerImpl* layer) const {
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->IsAnimatingOpacityProperty(layer->id(), tree_type)
-             : false;
+  return layer_tree_host_impl_->animation_host()->IsAnimatingOpacityProperty(
+      layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::IsAnimatingTransformProperty(const LayerImpl* layer) const {
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->IsAnimatingTransformProperty(layer->id(), tree_type)
-             : false;
+  return layer_tree_host_impl_->animation_host()->IsAnimatingTransformProperty(
+      layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::HasPotentiallyRunningFilterAnimation(
@@ -1916,10 +1908,7 @@ bool LayerTreeImpl::HasPotentiallyRunningFilterAnimation(
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasPotentiallyRunningFilterAnimation(layer->id(),
-                                                          tree_type)
-             : false;
+      ->HasPotentiallyRunningFilterAnimation(layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::HasPotentiallyRunningOpacityAnimation(
@@ -1927,10 +1916,7 @@ bool LayerTreeImpl::HasPotentiallyRunningOpacityAnimation(
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasPotentiallyRunningOpacityAnimation(layer->id(),
-                                                           tree_type)
-             : false;
+      ->HasPotentiallyRunningOpacityAnimation(layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::HasPotentiallyRunningTransformAnimation(
@@ -1938,66 +1924,49 @@ bool LayerTreeImpl::HasPotentiallyRunningTransformAnimation(
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasPotentiallyRunningTransformAnimation(layer->id(),
-                                                             tree_type)
-             : false;
+      ->HasPotentiallyRunningTransformAnimation(layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::HasAnyAnimationTargetingProperty(
     const LayerImpl* layer,
     TargetProperty::Type property) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasAnyAnimationTargetingProperty(layer->id(), property)
-             : false;
+      ->HasAnyAnimationTargetingProperty(layer->id(), property);
 }
 
 bool LayerTreeImpl::FilterIsAnimatingOnImplOnly(const LayerImpl* layer) const {
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->FilterIsAnimatingOnImplOnly(layer->id())
-             : false;
+  return layer_tree_host_impl_->animation_host()->FilterIsAnimatingOnImplOnly(
+      layer->id());
 }
 
 bool LayerTreeImpl::OpacityIsAnimatingOnImplOnly(const LayerImpl* layer) const {
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->OpacityIsAnimatingOnImplOnly(layer->id())
-             : false;
+  return layer_tree_host_impl_->animation_host()->OpacityIsAnimatingOnImplOnly(
+      layer->id());
 }
 
 bool LayerTreeImpl::ScrollOffsetIsAnimatingOnImplOnly(
     const LayerImpl* layer) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->ScrollOffsetIsAnimatingOnImplOnly(layer->id())
-             : false;
+      ->ScrollOffsetIsAnimatingOnImplOnly(layer->id());
 }
 
 bool LayerTreeImpl::TransformIsAnimatingOnImplOnly(
     const LayerImpl* layer) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->TransformIsAnimatingOnImplOnly(layer->id())
-             : false;
+      ->TransformIsAnimatingOnImplOnly(layer->id());
 }
 
 bool LayerTreeImpl::AnimationsPreserveAxisAlignment(
     const LayerImpl* layer) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->AnimationsPreserveAxisAlignment(layer->id())
-             : true;
+      ->AnimationsPreserveAxisAlignment(layer->id());
 }
 
 bool LayerTreeImpl::HasOnlyTranslationTransforms(const LayerImpl* layer) const {
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasOnlyTranslationTransforms(layer->id(), tree_type)
-             : true;
+  return layer_tree_host_impl_->animation_host()->HasOnlyTranslationTransforms(
+      layer->id(), tree_type);
 }
 
 bool LayerTreeImpl::MaximumTargetScale(const LayerImpl* layer,
@@ -2005,10 +1974,8 @@ bool LayerTreeImpl::MaximumTargetScale(const LayerImpl* layer,
   *max_scale = 0.f;
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()->MaximumTargetScale(
-                   layer->id(), tree_type, max_scale)
-             : true;
+  return layer_tree_host_impl_->animation_host()->MaximumTargetScale(
+      layer->id(), tree_type, max_scale);
 }
 
 bool LayerTreeImpl::AnimationStartScale(const LayerImpl* layer,
@@ -2016,43 +1983,33 @@ bool LayerTreeImpl::AnimationStartScale(const LayerImpl* layer,
   *start_scale = 0.f;
   LayerTreeType tree_type =
       IsActiveTree() ? LayerTreeType::ACTIVE : LayerTreeType::PENDING;
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()->AnimationStartScale(
-                   layer->id(), tree_type, start_scale)
-             : true;
+  return layer_tree_host_impl_->animation_host()->AnimationStartScale(
+      layer->id(), tree_type, start_scale);
 }
 
 bool LayerTreeImpl::HasFilterAnimationThatInflatesBounds(
     const LayerImpl* layer) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasFilterAnimationThatInflatesBounds(layer->id())
-             : false;
+      ->HasFilterAnimationThatInflatesBounds(layer->id());
 }
 
 bool LayerTreeImpl::HasTransformAnimationThatInflatesBounds(
     const LayerImpl* layer) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasTransformAnimationThatInflatesBounds(layer->id())
-             : false;
+      ->HasTransformAnimationThatInflatesBounds(layer->id());
 }
 
 bool LayerTreeImpl::HasAnimationThatInflatesBounds(
     const LayerImpl* layer) const {
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->HasAnimationThatInflatesBounds(layer->id())
-             : false;
+      ->HasAnimationThatInflatesBounds(layer->id());
 }
 
 bool LayerTreeImpl::FilterAnimationBoundsForBox(const LayerImpl* layer,
                                                 const gfx::BoxF& box,
                                                 gfx::BoxF* bounds) const {
-  return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->FilterAnimationBoundsForBox(layer->id(), box, bounds)
-             : false;
+  return layer_tree_host_impl_->animation_host()->FilterAnimationBoundsForBox(
+      layer->id(), box, bounds);
 }
 
 bool LayerTreeImpl::TransformAnimationBoundsForBox(const LayerImpl* layer,
@@ -2060,13 +2017,10 @@ bool LayerTreeImpl::TransformAnimationBoundsForBox(const LayerImpl* layer,
                                                    gfx::BoxF* bounds) const {
   *bounds = gfx::BoxF();
   return layer_tree_host_impl_->animation_host()
-             ? layer_tree_host_impl_->animation_host()
-                   ->TransformAnimationBoundsForBox(layer->id(), box, bounds)
-             : true;
+      ->TransformAnimationBoundsForBox(layer->id(), box, bounds);
 }
 
 void LayerTreeImpl::ScrollAnimationAbort(bool needs_completion) {
-  DCHECK(layer_tree_host_impl_->animation_host());
   layer_tree_host_impl_->animation_host()->ScrollAnimationAbort(
       needs_completion);
 }
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index eb2a649..cb4d427 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -59,7 +59,6 @@ LayerTreeSettings::LayerTreeSettings()
       use_external_begin_frame_source(false),
       main_frame_before_activation_enabled(false),
       using_synchronous_renderer_compositor(false),
-      accelerated_animation_enabled(true),
       can_use_lcd_text(true),
       use_distance_field_text(false),
       gpu_rasterization_enabled(false),
@@ -120,7 +119,6 @@ bool LayerTreeSettings::operator==(const LayerTreeSettings& other) const {
              other.main_frame_before_activation_enabled &&
          using_synchronous_renderer_compositor ==
              other.using_synchronous_renderer_compositor &&
-         accelerated_animation_enabled == other.accelerated_animation_enabled &&
          can_use_lcd_text == other.can_use_lcd_text &&
          use_distance_field_text == other.use_distance_field_text &&
          gpu_rasterization_enabled == other.gpu_rasterization_enabled &&
@@ -184,7 +182,6 @@ void LayerTreeSettings::ToProtobuf(proto::LayerTreeSettings* proto) const {
       main_frame_before_activation_enabled);
   proto->set_using_synchronous_renderer_compositor(
       using_synchronous_renderer_compositor);
-  proto->set_accelerated_animation_enabled(accelerated_animation_enabled);
   proto->set_can_use_lcd_text(can_use_lcd_text);
   proto->set_use_distance_field_text(use_distance_field_text);
   proto->set_gpu_rasterization_enabled(gpu_rasterization_enabled);
@@ -247,7 +244,6 @@ void LayerTreeSettings::FromProtobuf(const proto::LayerTreeSettings& proto) {
       proto.main_frame_before_activation_enabled();
   using_synchronous_renderer_compositor =
       proto.using_synchronous_renderer_compositor();
-  accelerated_animation_enabled = proto.accelerated_animation_enabled();
   can_use_lcd_text = proto.can_use_lcd_text();
   use_distance_field_text = proto.use_distance_field_text();
   gpu_rasterization_enabled = proto.gpu_rasterization_enabled();
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 3343c37..2aadbbc 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -41,7 +41,6 @@ class CC_EXPORT LayerTreeSettings {
   bool use_external_begin_frame_source;
   bool main_frame_before_activation_enabled;
   bool using_synchronous_renderer_compositor;
-  bool accelerated_animation_enabled;
   bool can_use_lcd_text;
   bool use_distance_field_text;
   bool gpu_rasterization_enabled;
diff --git a/cc/trees/layer_tree_settings_unittest.cc b/cc/trees/layer_tree_settings_unittest.cc
index 2d48596..8c10a1a 100644
--- a/cc/trees/layer_tree_settings_unittest.cc
+++ b/cc/trees/layer_tree_settings_unittest.cc
@@ -37,8 +37,6 @@ TEST(LayerTreeSettingsTest, AllMembersChanged) {
       !settings.main_frame_before_activation_enabled;
   settings.using_synchronous_renderer_compositor =
       !settings.using_synchronous_renderer_compositor;
-  settings.accelerated_animation_enabled =
-      !settings.accelerated_animation_enabled;
   settings.can_use_lcd_text = !settings.can_use_lcd_text;
   settings.use_distance_field_text = !settings.use_distance_field_text;
   settings.gpu_rasterization_enabled = !settings.gpu_rasterization_enabled;
@@ -109,7 +107,6 @@ TEST(LayerTreeSettingsTest, ArbitraryValues) {
   settings.use_external_begin_frame_source = true;
   settings.main_frame_before_activation_enabled = true;
   settings.using_synchronous_renderer_compositor = false;
-  settings.accelerated_animation_enabled = true;
   settings.can_use_lcd_text = false;
   settings.use_distance_field_text = false;
   settings.gpu_rasterization_enabled = false;