Unify the calculation of main thread offset of sticky element

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1079 matching lines @@
 
 void GraphicsLayer::SetBackdropFilters(CompositorFilterOperations filters) {
   PlatformLayer()->SetBackgroundFilters(filters.ReleaseCcFilterOperations());
 }
 
 void GraphicsLayer::SetStickyPositionConstraint(
     const WebLayerStickyPositionConstraint& sticky_constraint) {
   layer_->Layer()->SetStickyPositionConstraint(sticky_constraint);
 }
 
+void GraphicsLayer::SetStickyMainThreadOffset(const WebSize& offset) {
+  layer_->Layer()->SetStickyMainThreadOffset(offset);
+}
+
 void GraphicsLayer::SetFilterQuality(SkFilterQuality filter_quality) {
   if (image_layer_)
     image_layer_->SetNearestNeighbor(filter_quality == kNone_SkFilterQuality);
 }
 
 void GraphicsLayer::SetPaintingPhase(GraphicsLayerPaintingPhase phase) {
   if (painting_phase_ == phase)
     return;
   painting_phase_ = phase;
   SetNeedsDisplay();
@@ skipping 185 matching lines @@
 void showGraphicsLayerTree(const blink::GraphicsLayer* layer) {
   if (!layer) {
     LOG(INFO) << "Cannot showGraphicsLayerTree for (nil).";
     return;
   }
 
   String output = layer->LayerTreeAsText(blink::kLayerTreeIncludesDebugInfo);
   LOG(INFO) << output.Utf8().data();
 }
 #endif