cc: Move SyncedScrollOffset to scroll tree

cc/layers/layer_impl.cc

 // Copyright 2012 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_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 40 matching lines @@
                      int id,
                      scoped_refptr<SyncedScrollOffset> scroll_offset)
     : parent_(nullptr),
       scroll_parent_(nullptr),
       clip_parent_(nullptr),
       mask_layer_id_(-1),
       replica_layer_id_(-1),
       layer_id_(id),
       layer_tree_impl_(tree_impl),
       layer_list_impl_(tree_impl->list()),
-      scroll_offset_(scroll_offset),
       scroll_clip_layer_id_(Layer::INVALID_ID),
       main_thread_scrolling_reasons_(
           MainThreadScrollingReason::kNotScrollingOnMain),
       user_scrollable_horizontal_(true),
       user_scrollable_vertical_(true),
       double_sided_(true),
       should_flatten_transform_(true),
       should_flatten_transform_from_property_tree_(false),
       layer_property_changed_(false),
       masks_to_bounds_(false),
@@ skipping 410 matching lines @@
 
 bool LayerImpl::scrollable() const {
   return scroll_clip_layer_id_ != Layer::INVALID_ID;
 }
 
 bool LayerImpl::user_scrollable(ScrollbarOrientation orientation) const {
   return (orientation == HORIZONTAL) ? user_scrollable_horizontal_
                                      : user_scrollable_vertical_;
 }
 
-void LayerImpl::ApplySentScrollDeltasFromAbortedCommit() {
-  DCHECK(layer_tree_impl()->IsActiveTree());
-  scroll_offset_->AbortCommit();
-}
-
 skia::RefPtr<SkPicture> LayerImpl::GetPicture() {
   return skia::RefPtr<SkPicture>();
 }
 
 scoped_ptr<LayerImpl> LayerImpl::CreateLayerImpl(LayerTreeImpl* tree_impl) {
-  return LayerImpl::Create(tree_impl, layer_id_, scroll_offset_);
+  return LayerImpl::Create(tree_impl, layer_id_);
 }
 
 void LayerImpl::set_main_thread_scrolling_reasons(
     uint32_t main_thread_scrolling_reasons) {
   if (main_thread_scrolling_reasons_ == main_thread_scrolling_reasons)
     return;
 
   if (main_thread_scrolling_reasons &
           MainThreadScrollingReason::kHasNonLayerViewportConstrainedObjects &&
       layer_tree_impl()) {
@@ skipping 51 matching lines @@
     layer->NoteLayerPropertyChanged();
 
   layer->SetScrollClipLayer(scroll_clip_layer_id_);
   layer->SetElementId(element_id_);
   layer->SetMutableProperties(mutable_properties_);
   layer->set_user_scrollable_horizontal(user_scrollable_horizontal_);
   layer->set_user_scrollable_vertical(user_scrollable_vertical_);
 
   layer->SetScrollCompensationAdjustment(scroll_compensation_adjustment_);
 
-  layer->PushScrollOffset(nullptr);
-
   layer->Set3dSortingContextId(sorting_context_id_);
   layer->SetNumDescendantsThatDrawContent(num_descendants_that_draw_content_);
 
   layer->SetTransformTreeIndex(transform_tree_index_);
   layer->SetClipTreeIndex(clip_tree_index_);
   layer->SetEffectTreeIndex(effect_tree_index_);
   layer->SetScrollTreeIndex(scroll_tree_index_);
   layer->set_offset_to_transform_parent(offset_to_transform_parent_);
 
   LayerImpl* scroll_parent = nullptr;
@@ skipping 704 matching lines @@
   frame_timing_requests_ = requests;
   frame_timing_requests_dirty_ = true;
   SetNeedsPushProperties();
 }
 
 void LayerImpl::GatherFrameTimingRequestIds(std::vector<int64_t>* request_ids) {
   for (const auto& request : frame_timing_requests_)
     request_ids->push_back(request.id());
 }
 
+const SyncedScrollOffset* LayerImpl::synced_scroll_offset() const {

[ajuma, 2016/03/01 22:54:20]

Would it make sense (in a follow up CL) to move all the logic that needs to
directly work with a SyncedScrollOffset into the scroll tree, so LayerImpl
doesn't need know about how scroll offsets happen to be stored?

[sunxd, 2016/03/02 17:45:34]

Yeah, it makes sense. But there might be a lot of unit tests depending on these
interfaces. I will check it carefully in next CL.

+  return layer_tree_impl()->property_trees()->scroll_tree.synced_scroll_offset(
+      id());
+}
+
+SyncedScrollOffset* LayerImpl::synced_scroll_offset() {
+  return layer_tree_impl()->property_trees()->scroll_tree.synced_scroll_offset(
+      id());
+}
+
 void LayerImpl::SetTransform(const gfx::Transform& transform) {
   if (transform_ == transform)
     return;
 
   transform_ = transform;
   transform_is_invertible_ = transform_.IsInvertible();
   NoteLayerPropertyChangedForSubtree();
 }
 
 void LayerImpl::SetTransformAndInvertibility(const gfx::Transform& transform,
@@ skipping 125 matching lines @@
   update_rect_ = update_rect;
   SetNeedsPushProperties();
 }
 
 void LayerImpl::AddDamageRect(const gfx::Rect& damage_rect) {
   damage_rect_.Union(damage_rect);
 }
 
 void LayerImpl::SetCurrentScrollOffset(const gfx::ScrollOffset& scroll_offset) {
   DCHECK(IsActive());
-  if (scroll_offset_->SetCurrent(scroll_offset))
+  if (synced_scroll_offset()->SetCurrent(scroll_offset))
     DidUpdateScrollOffset();
 }
 
-void LayerImpl::PushScrollOffsetFromMainThread(
-    const gfx::ScrollOffset& scroll_offset) {
-  PushScrollOffset(&scroll_offset);
-}
-
-void LayerImpl::PushScrollOffsetFromMainThreadAndClobberActiveValue(
-    const gfx::ScrollOffset& scroll_offset) {
-  scroll_offset_->set_clobber_active_value();
-  PushScrollOffset(&scroll_offset);
-}
-
-gfx::ScrollOffset LayerImpl::PullDeltaForMainThread() {
-  // TODO(miletus): Remove all this temporary flooring machinery when
-  // Blink fully supports fractional scrolls.
-  gfx::ScrollOffset current_offset = CurrentScrollOffset();
-  gfx::ScrollOffset current_delta = IsActive()
-      ? scroll_offset_->Delta()
-      : scroll_offset_->PendingDelta().get();
-  gfx::ScrollOffset floored_delta(floor(current_delta.x()),
-                                  floor(current_delta.y()));
-  gfx::ScrollOffset diff_delta = floored_delta - current_delta;
-  gfx::ScrollOffset tmp_offset = current_offset + diff_delta;
-  scroll_offset_->SetCurrent(tmp_offset);
-  gfx::ScrollOffset delta = scroll_offset_->PullDeltaForMainThread();
-  scroll_offset_->SetCurrent(current_offset);
-  return delta;
-}
-
 gfx::ScrollOffset LayerImpl::CurrentScrollOffset() const {
-  return scroll_offset_->Current(IsActive());
+  return synced_scroll_offset()->Current(IsActive());
 }
 
 gfx::Vector2dF LayerImpl::ScrollDelta() const {
   if (IsActive())
-    return gfx::Vector2dF(scroll_offset_->Delta().x(),
-                          scroll_offset_->Delta().y());
+    return gfx::Vector2dF(synced_scroll_offset()->Delta().x(),
+                          synced_scroll_offset()->Delta().y());
   else
-    return gfx::Vector2dF(scroll_offset_->PendingDelta().get().x(),
-                          scroll_offset_->PendingDelta().get().y());
+    return gfx::Vector2dF(synced_scroll_offset()->PendingDelta().get().x(),
+                          synced_scroll_offset()->PendingDelta().get().y());
 }
 
 void LayerImpl::SetScrollDelta(const gfx::Vector2dF& delta) {
   DCHECK(IsActive());
   DCHECK(scrollable() || delta.IsZero());
-  SetCurrentScrollOffset(scroll_offset_->ActiveBase() +
+  SetCurrentScrollOffset(synced_scroll_offset()->ActiveBase() +
                          gfx::ScrollOffset(delta));
 }
 
 gfx::ScrollOffset LayerImpl::BaseScrollOffset() const {
   if (IsActive())
-    return scroll_offset_->ActiveBase();
+    return synced_scroll_offset()->ActiveBase();
   else
-    return scroll_offset_->PendingBase();
+    return synced_scroll_offset()->PendingBase();
 }
 
-void LayerImpl::PushScrollOffset(const gfx::ScrollOffset* scroll_offset) {
-  DCHECK(scroll_offset || IsActive());
+void LayerImpl::PushScrollOffsetFromMainThread(
+    const gfx::ScrollOffset& scroll_offset) {
   bool changed = false;
-  if (scroll_offset) {
-    DCHECK(!IsActive() || !layer_list_impl_->FindPendingLayerById(id()));
-    changed |= scroll_offset_->PushFromMainThread(*scroll_offset);
-  }
+  DCHECK(!IsActive() || !layer_list_impl_->FindPendingLayerById(id()));
+  changed |= synced_scroll_offset()->PushFromMainThread(scroll_offset);
+
   if (IsActive()) {
-    changed |= scroll_offset_->PushPendingToActive();
+    changed |= synced_scroll_offset()->PushPendingToActive();
   }
 
   if (changed)
     DidUpdateScrollOffset();
 }
 
 void LayerImpl::UpdatePropertyTreeScrollOffset() {
   // TODO(enne): in the future, scrolling should update the scroll tree
   // directly instead of going through layers.
   if (transform_tree_index_ != -1) {
     TransformTree& transform_tree =
         layer_tree_impl()->property_trees()->transform_tree;
     TransformNode* node = transform_tree.Node(transform_tree_index_);
-    gfx::ScrollOffset current_offset = scroll_offset_->Current(IsActive());
+    gfx::ScrollOffset current_offset =
+        synced_scroll_offset()->Current(IsActive());
     if (node->data.scroll_offset != current_offset) {
       node->data.scroll_offset = current_offset;
       node->data.needs_local_transform_update = true;
       transform_tree.set_needs_update(true);
     }
   }
 }
 
 void LayerImpl::DidUpdateScrollOffset() {
-  DCHECK(scroll_offset_);
-
   layer_tree_impl()->DidUpdateScrollState(id());
   NoteLayerPropertyChangedForSubtree();
-
   UpdatePropertyTreeScrollOffset();
 
   // Inform the pending twin that a property changed.
   if (layer_tree_impl()->IsActiveTree()) {
     LayerImpl* pending_twin = layer_list_impl_->FindPendingLayerById(id());
     if (pending_twin)
       pending_twin->DidUpdateScrollOffset();
   }
 }
 
@@ skipping 80 matching lines @@
 
   state->SetInteger("draws_content", DrawsContent());
   state->SetInteger("gpu_memory_usage",
                     base::saturated_cast<int>(GPUMemoryUsageInBytes()));
 
   if (mutable_properties_ != MutableProperty::kNone) {
     state->SetInteger("element_id", base::saturated_cast<int>(element_id_));
     state->SetInteger("mutable_properties", mutable_properties_);
   }
 
-  MathUtil::AddToTracedValue(
-      "scroll_offset", scroll_offset_ ? scroll_offset_->Current(IsActive())
-                                      : gfx::ScrollOffset(),
-      state);
+  MathUtil::AddToTracedValue("scroll_offset",
+                             synced_scroll_offset()
+                                 ? synced_scroll_offset()->Current(IsActive())
+                                 : gfx::ScrollOffset(),
+                             state);
 
   MathUtil::AddToTracedValue("transform_origin", transform_origin_, state);
 
   bool clipped;
   gfx::QuadF layer_quad =
       MathUtil::MapQuad(ScreenSpaceTransform(),
                         gfx::QuadF(gfx::RectF(gfx::Rect(bounds()))), &clipped);
   MathUtil::AddToTracedValue("layer_quad", layer_quad, state);
   if (!touch_event_handler_region_.IsEmpty()) {
     state->BeginArray("touch_event_handler_region");
@@ skipping 176 matching lines @@
            .layer_transforms_should_scale_layer_contents) {
     return default_scale;
   }
 
   gfx::Vector2dF transform_scales = MathUtil::ComputeTransform2dScaleComponents(
       DrawTransform(), default_scale);
   return std::max(transform_scales.x(), transform_scales.y());
 }
 
 }  // namespace cc