// Copyright 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/layers/layer.h"

#include <algorithm>

#include "base/location.h"
#include "base/metrics/histogram.h"
#include "base/single_thread_task_runner.h"
#include "cc/animation/animation.h"
#include "cc/animation/animation_events.h"
#include "cc/animation/layer_animation_controller.h"
#include "cc/layers/layer_impl.h"
#include "cc/output/copy_output_request.h"
#include "cc/output/copy_output_result.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_impl.h"
#include "third_party/skia/include/core/SkImageFilter.h"
#include "ui/gfx/rect_conversions.h"

namespace cc {

static int s_next_layer_id = 1;

scoped_refptr<Layer> Layer::Create() {
  return make_scoped_refptr(new Layer());
}

Layer::Layer()
    : needs_display_(false),
      stacking_order_changed_(false),
      layer_id_(s_next_layer_id++),
      ignore_set_needs_commit_(false),
      parent_(NULL),
      layer_tree_host_(NULL),
      scrollable_(false),
      should_scroll_on_main_thread_(false),
      have_wheel_event_handlers_(false),
      anchor_point_(0.5f, 0.5f),
      background_color_(0),
      compositing_reasons_(kCompositingReasonUnknown),
      opacity_(1.f),
      anchor_point_z_(0.f),
      is_container_for_fixed_position_layers_(false),
      is_drawable_(false),
      hide_layer_and_subtree_(false),
      masks_to_bounds_(false),
      contents_opaque_(false),
      double_sided_(true),
      preserves_3d_(false),
      use_parent_backface_visibility_(false),
      draw_checkerboard_for_missing_tiles_(false),
      force_render_surface_(false),
      replica_layer_(NULL),
      raster_scale_(0.f) {
  if (layer_id_ < 0) {
    s_next_layer_id = 1;
    layer_id_ = s_next_layer_id++;
  }

  layer_animation_controller_ = LayerAnimationController::Create(layer_id_);
  layer_animation_controller_->AddValueObserver(this);
}

Layer::~Layer() {
  // Our parent should be holding a reference to us so there should be no
  // way for us to be destroyed while we still have a parent.
  DCHECK(!parent());

  layer_animation_controller_->RemoveValueObserver(this);

  // Remove the parent reference from all children and dependents.
  RemoveAllChildren();
  if (mask_layer_.get()) {
    DCHECK_EQ(this, mask_layer_->parent());
    mask_layer_->RemoveFromParent();
  }
  if (replica_layer_.get()) {
    DCHECK_EQ(this, replica_layer_->parent());
    replica_layer_->RemoveFromParent();
  }
}

void Layer::SetLayerTreeHost(LayerTreeHost* host) {
  if (layer_tree_host_ == host)
    return;

  layer_tree_host_ = host;

  for (size_t i = 0; i < children_.size(); ++i)
    children_[i]->SetLayerTreeHost(host);

  if (mask_layer_.get())
    mask_layer_->SetLayerTreeHost(host);
  if (replica_layer_.get())
    replica_layer_->SetLayerTreeHost(host);

  if (host) {
    layer_animation_controller_->SetAnimationRegistrar(
        host->animation_registrar());

    if (host->settings().layer_transforms_should_scale_layer_contents)
      reset_raster_scale_to_unknown();
  }

  if (host && layer_animation_controller_->has_any_animation())
    host->SetNeedsCommit();
  if (host &&
      (!filters_.IsEmpty() || !background_filters_.IsEmpty() || filter_))
    layer_tree_host_->set_needs_filter_context();
}

void Layer::SetNeedsCommit() {
  if (ignore_set_needs_commit_)
    return;
  if (layer_tree_host_)
    layer_tree_host_->SetNeedsCommit();
}

void Layer::SetNeedsFullTreeSync() {
  if (layer_tree_host_)
    layer_tree_host_->SetNeedsFullTreeSync();
}

bool Layer::IsPropertyChangeAllowed() const {
  if (!layer_tree_host_)
    return true;

  if (!layer_tree_host_->settings().strict_layer_property_change_checking)
    return true;

  return !layer_tree_host_->in_paint_layer_contents();
}

gfx::Rect Layer::LayerRectToContentRect(const gfx::RectF& layer_rect) const {
  gfx::RectF content_rect =
      gfx::ScaleRect(layer_rect, contents_scale_x(), contents_scale_y());
  // Intersect with content rect to avoid the extra pixel because for some
  // values x and y, ceil((x / y) * y) may be x + 1.
  content_rect.Intersect(gfx::Rect(content_bounds()));
  return gfx::ToEnclosingRect(content_rect);
}

bool Layer::BlocksPendingCommit() const {
  return false;
}

bool Layer::CanClipSelf() const {
  return false;
}

bool Layer::BlocksPendingCommitRecursive() const {
  if (BlocksPendingCommit())
    return true;
  if (mask_layer() && mask_layer()->BlocksPendingCommitRecursive())
    return true;
  if (replica_layer() && replica_layer()->BlocksPendingCommitRecursive())
    return true;
  for (size_t i = 0; i < children_.size(); ++i) {
    if (children_[i]->BlocksPendingCommitRecursive())
      return true;
  }
  return false;
}

void Layer::SetParent(Layer* layer) {
  DCHECK(!layer || !layer->HasAncestor(this));
  parent_ = layer;
  SetLayerTreeHost(parent_ ? parent_->layer_tree_host() : NULL);

  if (!layer_tree_host_)
    return;
  const LayerTreeSettings& settings = layer_tree_host_->settings();
  if (!settings.layer_transforms_should_scale_layer_contents)
    return;

  reset_raster_scale_to_unknown();
  if (mask_layer_.get())
    mask_layer_->reset_raster_scale_to_unknown();
  if (replica_layer_.get() && replica_layer_->mask_layer_.get())
    replica_layer_->mask_layer_->reset_raster_scale_to_unknown();
}

bool Layer::HasAncestor(Layer* ancestor) const {
  for (const Layer* layer = parent(); layer; layer = layer->parent()) {
    if (layer == ancestor)
      return true;
  }
  return false;
}

void Layer::AddChild(scoped_refptr<Layer> child) {
  InsertChild(child, children_.size());
}

void Layer::InsertChild(scoped_refptr<Layer> child, size_t index) {
  DCHECK(IsPropertyChangeAllowed());
  child->RemoveFromParent();
  child->SetParent(this);
  child->stacking_order_changed_ = true;

  index = std::min(index, children_.size());
  children_.insert(children_.begin() + index, child);
  SetNeedsFullTreeSync();
}

void Layer::RemoveFromParent() {
  DCHECK(IsPropertyChangeAllowed());
  if (parent_)
    parent_->RemoveChildOrDependent(this);
}

void Layer::RemoveChildOrDependent(Layer* child) {
  if (mask_layer_.get() == child) {
    mask_layer_->SetParent(NULL);
    mask_layer_ = NULL;
    SetNeedsFullTreeSync();
    return;
  }
  if (replica_layer_.get() == child) {
    replica_layer_->SetParent(NULL);
    replica_layer_ = NULL;
    SetNeedsFullTreeSync();
    return;
  }

  for (LayerList::iterator iter = children_.begin();
       iter != children_.end();
       ++iter) {
    if (iter->get() != child)
      continue;

    child->SetParent(NULL);
    children_.erase(iter);
    SetNeedsFullTreeSync();
    return;
  }
}

void Layer::ReplaceChild(Layer* reference, scoped_refptr<Layer> new_layer) {
  DCHECK(reference);
  DCHECK_EQ(reference->parent(), this);
  DCHECK(IsPropertyChangeAllowed());

  if (reference == new_layer.get())
    return;

  int reference_index = IndexOfChild(reference);
  if (reference_index == -1) {
    NOTREACHED();
    return;
  }

  reference->RemoveFromParent();

  if (new_layer.get()) {
    new_layer->RemoveFromParent();
    InsertChild(new_layer, reference_index);
  }
}

int Layer::IndexOfChild(const Layer* reference) {
  for (size_t i = 0; i < children_.size(); ++i) {
    if (children_[i].get() == reference)
      return i;
  }
  return -1;
}

void Layer::SetBounds(gfx::Size size) {
  DCHECK(IsPropertyChangeAllowed());
  if (bounds() == size)
    return;

  bool first_resize = bounds().IsEmpty() && !size.IsEmpty();

  bounds_ = size;

  if (first_resize)
    SetNeedsDisplay();
  else
    SetNeedsCommit();
}

Layer* Layer::RootLayer() {
  Layer* layer = this;
  while (layer->parent())
    layer = layer->parent();
  return layer;
}

void Layer::RemoveAllChildren() {
  DCHECK(IsPropertyChangeAllowed());
  while (children_.size()) {
    Layer* layer = children_[0].get();
    DCHECK_EQ(this, layer->parent());
    layer->RemoveFromParent();
  }
}

void Layer::SetChildren(const LayerList& children) {
  DCHECK(IsPropertyChangeAllowed());
  if (children == children_)
    return;

  RemoveAllChildren();
  for (size_t i = 0; i < children.size(); ++i)
    AddChild(children[i]);
}

void Layer::RequestCopyOfOutput(
    scoped_ptr<CopyOutputRequest> request) {
  DCHECK(IsPropertyChangeAllowed());
  if (request->IsEmpty())
    return;
  copy_requests_.push_back(request.Pass());
  SetNeedsCommit();
}

void Layer::SetAnchorPoint(gfx::PointF anchor_point) {
  DCHECK(IsPropertyChangeAllowed());
  if (anchor_point_ == anchor_point)
    return;
  anchor_point_ = anchor_point;
  SetNeedsCommit();
}

void Layer::SetAnchorPointZ(float anchor_point_z) {
  DCHECK(IsPropertyChangeAllowed());
  if (anchor_point_z_ == anchor_point_z)
    return;
  anchor_point_z_ = anchor_point_z;
  SetNeedsCommit();
}

void Layer::SetBackgroundColor(SkColor background_color) {
  DCHECK(IsPropertyChangeAllowed());
  if (background_color_ == background_color)
    return;
  background_color_ = background_color;
  SetNeedsCommit();
}

SkColor Layer::SafeOpaqueBackgroundColor() const {
  SkColor color = background_color();
  if (SkColorGetA(color) == 255 && !contents_opaque()) {
    color = SK_ColorTRANSPARENT;
  } else if (SkColorGetA(color) != 255 && contents_opaque()) {
    for (const Layer* layer = parent(); layer;
         layer = layer->parent()) {
      color = layer->background_color();
      if (SkColorGetA(color) == 255)
        break;
    }
    if (SkColorGetA(color) != 255)
      color = layer_tree_host_->background_color();
    if (SkColorGetA(color) != 255)
      color = SkColorSetA(color, 255);
  }
  return color;
}

void Layer::CalculateContentsScale(
    float ideal_contents_scale,
    float device_scale_factor,
    float page_scale_factor,
    bool animating_transform_to_screen,
    float* contents_scale_x,
    float* contents_scale_y,
    gfx::Size* content_bounds) {
  *contents_scale_x = 1;
  *contents_scale_y = 1;
  *content_bounds = bounds();
}

void Layer::SetMasksToBounds(bool masks_to_bounds) {
  DCHECK(IsPropertyChangeAllowed());
  if (masks_to_bounds_ == masks_to_bounds)
    return;
  masks_to_bounds_ = masks_to_bounds;
  SetNeedsCommit();
}

void Layer::SetMaskLayer(Layer* mask_layer) {
  DCHECK(IsPropertyChangeAllowed());
  if (mask_layer_.get() == mask_layer)
    return;
  if (mask_layer_.get()) {
    DCHECK_EQ(this, mask_layer_->parent());
    mask_layer_->RemoveFromParent();
  }
  mask_layer_ = mask_layer;
  if (mask_layer_.get()) {
    DCHECK(!mask_layer_->parent());
    mask_layer_->RemoveFromParent();
    mask_layer_->SetParent(this);
    mask_layer_->SetIsMask(true);
  }
  SetNeedsFullTreeSync();
}

void Layer::SetReplicaLayer(Layer* layer) {
  DCHECK(IsPropertyChangeAllowed());
  if (replica_layer_.get() == layer)
    return;
  if (replica_layer_.get()) {
    DCHECK_EQ(this, replica_layer_->parent());
    replica_layer_->RemoveFromParent();
  }
  replica_layer_ = layer;
  if (replica_layer_.get()) {
    DCHECK(!replica_layer_->parent());
    replica_layer_->RemoveFromParent();
    replica_layer_->SetParent(this);
  }
  SetNeedsFullTreeSync();
}

void Layer::SetFilters(const FilterOperations& filters) {
  DCHECK(IsPropertyChangeAllowed());
  if (filters_ == filters)
    return;
  DCHECK(!filter_);
  filters_ = filters;
  SetNeedsCommit();
  if (!filters.IsEmpty() && layer_tree_host_)
    layer_tree_host_->set_needs_filter_context();
}

void Layer::SetFilter(const skia::RefPtr<SkImageFilter>& filter) {
  DCHECK(IsPropertyChangeAllowed());
  if (filter_.get() == filter.get())
    return;
  DCHECK(filters_.IsEmpty());
  filter_ = filter;
  SetNeedsCommit();
  if (filter && layer_tree_host_)
    layer_tree_host_->set_needs_filter_context();
}

void Layer::SetBackgroundFilters(const FilterOperations& filters) {
  DCHECK(IsPropertyChangeAllowed());
  if (background_filters_ == filters)
    return;
  background_filters_ = filters;
  SetNeedsCommit();
  if (!filters.IsEmpty() && layer_tree_host_)
    layer_tree_host_->set_needs_filter_context();
}

void Layer::SetOpacity(float opacity) {
  DCHECK(IsPropertyChangeAllowed());
  if (opacity_ == opacity)
    return;
  opacity_ = opacity;
  SetNeedsCommit();
}

bool Layer::OpacityIsAnimating() const {
  return layer_animation_controller_->IsAnimatingProperty(Animation::Opacity);
}

bool Layer::OpacityCanAnimateOnImplThread() const {
  return false;
}

void Layer::SetContentsOpaque(bool opaque) {
  DCHECK(IsPropertyChangeAllowed());
  if (contents_opaque_ == opaque)
    return;
  contents_opaque_ = opaque;
  SetNeedsCommit();
}

void Layer::SetPosition(gfx::PointF position) {
  DCHECK(IsPropertyChangeAllowed());
  if (position_ == position)
    return;
  position_ = position;
  SetNeedsCommit();
}

bool Layer::IsContainerForFixedPositionLayers() const {
  if (!transform_.IsIdentityOrTranslation())
    return true;
  if (parent_ && !parent_->sublayer_transform_.IsIdentityOrTranslation())
    return true;
  return is_container_for_fixed_position_layers_;
}

void Layer::SetSublayerTransform(const gfx::Transform& sublayer_transform) {
  DCHECK(IsPropertyChangeAllowed());
  if (sublayer_transform_ == sublayer_transform)
    return;
  sublayer_transform_ = sublayer_transform;
  SetNeedsCommit();
}

void Layer::SetTransform(const gfx::Transform& transform) {
  DCHECK(IsPropertyChangeAllowed());
  if (transform_ == transform)
    return;
  transform_ = transform;
  SetNeedsCommit();
}

bool Layer::TransformIsAnimating() const {
  return layer_animation_controller_->IsAnimatingProperty(Animation::Transform);
}

void Layer::SetScrollOffset(gfx::Vector2d scroll_offset) {
  DCHECK(IsPropertyChangeAllowed());
  if (scroll_offset_ == scroll_offset)
    return;
  scroll_offset_ = scroll_offset;
  SetNeedsCommit();
}

void Layer::SetScrollOffsetFromImplSide(gfx::Vector2d scroll_offset) {
  DCHECK(IsPropertyChangeAllowed());
  DCHECK(layer_tree_host_ && layer_tree_host_->CommitRequested());
  if (scroll_offset_ == scroll_offset)
    return;
  scroll_offset_ = scroll_offset;
  if (!did_scroll_callback_.is_null())
    did_scroll_callback_.Run();
  // Note: didScroll() could potentially change the layer structure.
  //       "this" may have been destroyed during the process.
}

void Layer::SetMaxScrollOffset(gfx::Vector2d max_scroll_offset) {
  DCHECK(IsPropertyChangeAllowed());
  if (max_scroll_offset_ == max_scroll_offset)
    return;
  max_scroll_offset_ = max_scroll_offset;
  SetNeedsCommit();
}

void Layer::SetScrollable(bool scrollable) {
  DCHECK(IsPropertyChangeAllowed());
  if (scrollable_ == scrollable)
    return;
  scrollable_ = scrollable;
  SetNeedsCommit();
}

void Layer::SetShouldScrollOnMainThread(bool should_scroll_on_main_thread) {
  DCHECK(IsPropertyChangeAllowed());
  if (should_scroll_on_main_thread_ == should_scroll_on_main_thread)
    return;
  should_scroll_on_main_thread_ = should_scroll_on_main_thread;
  SetNeedsCommit();
}

void Layer::SetHaveWheelEventHandlers(bool have_wheel_event_handlers) {
  DCHECK(IsPropertyChangeAllowed());
  if (have_wheel_event_handlers_ == have_wheel_event_handlers)
    return;
  have_wheel_event_handlers_ = have_wheel_event_handlers;
  SetNeedsCommit();
}

void Layer::SetNonFastScrollableRegion(const Region& region) {
  DCHECK(IsPropertyChangeAllowed());
  if (non_fast_scrollable_region_ == region)
    return;
  non_fast_scrollable_region_ = region;
  SetNeedsCommit();
}

void Layer::SetTouchEventHandlerRegion(const Region& region) {
  DCHECK(IsPropertyChangeAllowed());
  if (touch_event_handler_region_ == region)
    return;
  touch_event_handler_region_ = region;
}

void Layer::SetDrawCheckerboardForMissingTiles(bool checkerboard) {
  DCHECK(IsPropertyChangeAllowed());
  if (draw_checkerboard_for_missing_tiles_ == checkerboard)
    return;
  draw_checkerboard_for_missing_tiles_ = checkerboard;
  SetNeedsCommit();
}

void Layer::SetForceRenderSurface(bool force) {
  DCHECK(IsPropertyChangeAllowed());
  if (force_render_surface_ == force)
    return;
  force_render_surface_ = force;
  SetNeedsCommit();
}

void Layer::SetDoubleSided(bool double_sided) {
  DCHECK(IsPropertyChangeAllowed());
  if (double_sided_ == double_sided)
    return;
  double_sided_ = double_sided;
  SetNeedsCommit();
}

void Layer::SetIsDrawable(bool is_drawable) {
  DCHECK(IsPropertyChangeAllowed());
  if (is_drawable_ == is_drawable)
    return;

  is_drawable_ = is_drawable;
  SetNeedsCommit();
}

void Layer::SetHideLayerAndSubtree(bool hide) {
  DCHECK(IsPropertyChangeAllowed());
  if (hide_layer_and_subtree_ == hide)
    return;

  hide_layer_and_subtree_ = hide;
  SetNeedsCommit();
}

void Layer::SetNeedsDisplayRect(const gfx::RectF& dirty_rect) {
  update_rect_.Union(dirty_rect);
  needs_display_ = true;

  // Simply mark the contents as dirty. For non-root layers, the call to
  // SetNeedsCommit will schedule a fresh compositing pass.
  // For the root layer, SetNeedsCommit has no effect.
  if (DrawsContent() && !update_rect_.IsEmpty())
    SetNeedsCommit();
}

bool Layer::DescendantIsFixedToContainerLayer() const {
  for (size_t i = 0; i < children_.size(); ++i) {
    if (children_[i]->position_constraint_.is_fixed_position() ||
        children_[i]->DescendantIsFixedToContainerLayer())
      return true;
  }
  return false;
}

void Layer::SetIsContainerForFixedPositionLayers(bool container) {
  if (is_container_for_fixed_position_layers_ == container)
    return;
  is_container_for_fixed_position_layers_ = container;

  if (layer_tree_host_ && layer_tree_host_->CommitRequested())
    return;

  // Only request a commit if we have a fixed positioned descendant.
  if (DescendantIsFixedToContainerLayer())
    SetNeedsCommit();
}

void Layer::SetPositionConstraint(const LayerPositionConstraint& constraint) {
  DCHECK(IsPropertyChangeAllowed());
  if (position_constraint_ == constraint)
    return;
  position_constraint_ = constraint;
  SetNeedsCommit();
}

static void RunCopyCallbackOnMainThread(scoped_ptr<CopyOutputRequest> request,
                                        scoped_ptr<CopyOutputResult> result) {
  request->SendResult(result.Pass());
}

static void PostCopyCallbackToMainThread(
    scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner,
    scoped_ptr<CopyOutputRequest> request,
    scoped_ptr<CopyOutputResult> result) {
  main_thread_task_runner->PostTask(FROM_HERE,
                                    base::Bind(&RunCopyCallbackOnMainThread,
                                               base::Passed(&request),
                                               base::Passed(&result)));
}

void Layer::PushPropertiesTo(LayerImpl* layer) {
  layer->SetAnchorPoint(anchor_point_);
  layer->SetAnchorPointZ(anchor_point_z_);
  layer->SetBackgroundColor(background_color_);
  layer->SetBounds(paint_properties_.bounds);
  layer->SetContentBounds(content_bounds());
  layer->SetContentsScale(contents_scale_x(), contents_scale_y());
  layer->SetDebugName(debug_name_);
  layer->SetCompositingReasons(compositing_reasons_);
  layer->SetDoubleSided(double_sided_);
  layer->SetDrawCheckerboardForMissingTiles(
      draw_checkerboard_for_missing_tiles_);
  layer->SetForceRenderSurface(force_render_surface_);
  layer->SetDrawsContent(DrawsContent());
  layer->SetHideLayerAndSubtree(hide_layer_and_subtree_);
  layer->SetFilters(filters());
  layer->SetFilter(filter());
  layer->SetBackgroundFilters(background_filters());
  layer->SetMasksToBounds(masks_to_bounds_);
  layer->SetShouldScrollOnMainThread(should_scroll_on_main_thread_);
  layer->SetHaveWheelEventHandlers(have_wheel_event_handlers_);
  layer->SetNonFastScrollableRegion(non_fast_scrollable_region_);
  layer->SetTouchEventHandlerRegion(touch_event_handler_region_);
  layer->SetContentsOpaque(contents_opaque_);
  if (!layer->OpacityIsAnimatingOnImplOnly() && !OpacityIsAnimating())
    layer->SetOpacity(opacity_);
  DCHECK(!(OpacityIsAnimating() && layer->OpacityIsAnimatingOnImplOnly()));
  layer->SetPosition(position_);
  layer->SetIsContainerForFixedPositionLayers(
      IsContainerForFixedPositionLayers());
  layer->SetFixedContainerSizeDelta(gfx::Vector2dF());
  layer->SetPositionConstraint(position_constraint_);
  layer->SetPreserves3d(preserves_3d());
  layer->SetUseParentBackfaceVisibility(use_parent_backface_visibility_);
  layer->SetSublayerTransform(sublayer_transform_);
  if (!layer->TransformIsAnimatingOnImplOnly() && !TransformIsAnimating())
    layer->SetTransform(transform_);
  DCHECK(!(TransformIsAnimating() && layer->TransformIsAnimatingOnImplOnly()));

  layer->SetScrollable(scrollable_);
  layer->SetScrollOffset(scroll_offset_);
  layer->SetMaxScrollOffset(max_scroll_offset_);

  // Wrap the copy_requests_ in a PostTask to the main thread.
  ScopedPtrVector<CopyOutputRequest> main_thread_copy_requests;
  for (ScopedPtrVector<CopyOutputRequest>::iterator it = copy_requests_.begin();
       it != copy_requests_.end();
       ++it) {
    scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner =
        layer_tree_host()->proxy()->MainThreadTaskRunner();
    scoped_ptr<CopyOutputRequest> original_request = copy_requests_.take(it);
    const CopyOutputRequest& original_request_ref = *original_request;
    scoped_ptr<CopyOutputRequest> main_thread_request =
        CopyOutputRequest::CreateRelayRequest(
            original_request_ref,
            base::Bind(&PostCopyCallbackToMainThread,
                       main_thread_task_runner,
                       base::Passed(&original_request)));
    main_thread_copy_requests.push_back(main_thread_request.Pass());
  }
  copy_requests_.clear();
  layer->PassCopyRequests(&main_thread_copy_requests);

  // If the main thread commits multiple times before the impl thread actually
  // draws, then damage tracking will become incorrect if we simply clobber the
  // update_rect here. The LayerImpl's update_rect needs to accumulate (i.e.
  // union) any update changes that have occurred on the main thread.
  update_rect_.Union(layer->update_rect());
  layer->set_update_rect(update_rect_);

  if (layer->layer_tree_impl()->settings().impl_side_painting) {
    DCHECK(layer->layer_tree_impl()->IsPendingTree());
    LayerImpl* active_twin =
        layer->layer_tree_impl()->FindActiveTreeLayerById(id());
    // Update the scroll delta from the active layer, which may have
    // adjusted its scroll delta prior to this pending layer being created.
    // This code is identical to that in LayerImpl::SetScrollDelta.
    if (active_twin) {
      DCHECK(layer->sent_scroll_delta().IsZero());
      layer->SetScrollDelta(active_twin->ScrollDelta() -
                            active_twin->sent_scroll_delta());
    }
  } else {
    layer->SetScrollDelta(layer->ScrollDelta() - layer->sent_scroll_delta());
    layer->SetSentScrollDelta(gfx::Vector2d());
  }

  layer->SetStackingOrderChanged(stacking_order_changed_);

  layer_animation_controller_->PushAnimationUpdatesTo(
      layer->layer_animation_controller());

  // Reset any state that should be cleared for the next update.
  stacking_order_changed_ = false;
  update_rect_ = gfx::RectF();
}

scoped_ptr<LayerImpl> Layer::CreateLayerImpl(LayerTreeImpl* tree_impl) {
  return LayerImpl::Create(tree_impl, layer_id_);
}

bool Layer::DrawsContent() const {
  return is_drawable_;
}

void Layer::SavePaintProperties() {
  // TODO(reveman): Save all layer properties that we depend on not
  // changing until PushProperties() has been called. crbug.com/231016
  paint_properties_.bounds = bounds_;
}

bool Layer::Update(ResourceUpdateQueue* queue,
                   const OcclusionTracker* occlusion) {
  return false;
}

bool Layer::NeedMoreUpdates() {
  return false;
}

void Layer::SetDebugName(const std::string& debug_name) {
  debug_name_ = debug_name;
  SetNeedsCommit();
}

void Layer::SetCompositingReasons(CompositingReasons reasons) {
  compositing_reasons_ = reasons;
}

void Layer::CreateRenderSurface() {
  DCHECK(!draw_properties_.render_surface);
  draw_properties_.render_surface = make_scoped_ptr(new RenderSurface(this));
  draw_properties_.render_target = this;
}

void Layer::ClearRenderSurface() {
  draw_properties_.render_surface.reset();
}

void Layer::OnOpacityAnimated(float opacity) {
  // This is called due to an ongoing accelerated animation. Since this
  // animation is also being run on the impl thread, there is no need to request
  // a commit to push this value over, so set the value directly rather than
  // calling SetOpacity.
  opacity_ = opacity;
}

void Layer::OnTransformAnimated(const gfx::Transform& transform) {
  // This is called due to an ongoing accelerated animation. Since this
  // animation is also being run on the impl thread, there is no need to request
  // a commit to push this value over, so set this value directly rather than
  // calling SetTransform.
  transform_ = transform;
}

bool Layer::IsActive() const {
  return true;
}

bool Layer::AddAnimation(scoped_ptr <Animation> animation) {
  if (!layer_animation_controller_->animation_registrar())
    return false;

  UMA_HISTOGRAM_BOOLEAN("Renderer.AnimationAddedToOrphanLayer",
                        !layer_tree_host_);
  layer_animation_controller_->AddAnimation(animation.Pass());
  SetNeedsCommit();
  return true;
}

void Layer::PauseAnimation(int animation_id, double time_offset) {
  layer_animation_controller_->PauseAnimation(animation_id, time_offset);
  SetNeedsCommit();
}

void Layer::RemoveAnimation(int animation_id) {
  layer_animation_controller_->RemoveAnimation(animation_id);
  SetNeedsCommit();
}

void Layer::SuspendAnimations(double monotonic_time) {
  layer_animation_controller_->SuspendAnimations(monotonic_time);
  SetNeedsCommit();
}

void Layer::ResumeAnimations(double monotonic_time) {
  layer_animation_controller_->ResumeAnimations(monotonic_time);
  SetNeedsCommit();
}

void Layer::SetLayerAnimationControllerForTest(
    scoped_refptr<LayerAnimationController> controller) {
  layer_animation_controller_->RemoveValueObserver(this);
  layer_animation_controller_ = controller;
  layer_animation_controller_->set_force_sync();
  layer_animation_controller_->AddValueObserver(this);
  SetNeedsCommit();
}

bool Layer::HasActiveAnimation() const {
  return layer_animation_controller_->HasActiveAnimation();
}

void Layer::AddLayerAnimationEventObserver(
    LayerAnimationEventObserver* animation_observer) {
  layer_animation_controller_->AddEventObserver(animation_observer);
}

void Layer::RemoveLayerAnimationEventObserver(
    LayerAnimationEventObserver* animation_observer) {
  layer_animation_controller_->RemoveEventObserver(animation_observer);
}

Region Layer::VisibleContentOpaqueRegion() const {
  if (contents_opaque())
    return visible_content_rect();
  return Region();
}

ScrollbarLayer* Layer::ToScrollbarLayer() {
  return NULL;
}

RenderingStatsInstrumentation* Layer::rendering_stats_instrumentation() const {
  return layer_tree_host_->rendering_stats_instrumentation();
}

bool Layer::SupportsLCDText() const {
  return false;
}

}  // namespace cc