Move overscroll bounce to impl thread

cc/trees/tree_scroll_elasticity_client.cc

+// Copyright 2014 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/trees/tree_scroll_elasticity_client.h"
+
+#include "cc/layers/layer_impl.h"
+#include "cc/trees/layer_tree_host_impl.h"
+
+namespace cc {
+
+TreeScrollElasticityClient::TreeScrollElasticityClient(LayerTreeHostImpl* tree) 
+  : tree_(tree), timer_active_(false), controller_(NULL) {}
+
+TreeScrollElasticityClient::~TreeScrollElasticityClient() {}
+
+void TreeScrollElasticityClient::BindToController(
+    ScrollElasticityController* controller) {
+  controller_ = controller;
+}
+
+bool TreeScrollElasticityClient::allowsHorizontalStretching() const {
+  return true;
+}
+
+bool TreeScrollElasticityClient::allowsVerticalStretching() const {
+  return true;
+}
+
+// The amount that the view is stretched past the normal allowable bounds.
+// The "overhang" amount.
+gfx::Vector2dF TreeScrollElasticityClient::stretchAmount() const {
+  return stretch_offset_;
+}
+
+bool TreeScrollElasticityClient::pinnedInDirection(const gfx::Vector2dF& delta) const {
+  LayerImpl* layer = tree_->InnerViewportScrollLayer();
+  bool result = false;
+  if (delta.x() < 0)
+    result |= layer->TotalScrollOffset().x() <= 0;
+  if (delta.x() > 0)
+    result |= layer->TotalScrollOffset().x() >= layer->MaxScrollOffset().x();
+  if (delta.y() < 0)
+    result |= layer->TotalScrollOffset().y() <= 0;
+  if (delta.y() > 0)
+    result |= layer->TotalScrollOffset().y() >= layer->MaxScrollOffset().y();
+  printf("pinned delta=%s offset=%s max=%s : %d\n",
+      delta.ToString().c_str(),
+      layer->TotalScrollOffset().ToString().c_str(), 
+      layer->MaxScrollOffset().ToString().c_str(),
+      result);
+  return result;
+}
+
+bool TreeScrollElasticityClient::canScrollHorizontally() const {
+  return true;
+}
+
+bool TreeScrollElasticityClient::canScrollVertically() const {
+  return true;
+}
+
+// Return the absolute scroll position, not relative to the scroll origin.
+gfx::Vector2dF TreeScrollElasticityClient::absoluteScrollPosition() const {
+  return stretchAmount();
+}
+
+void TreeScrollElasticityClient::immediateScrollBy(const gfx::Vector2dF& delta) {
+}
+
+void TreeScrollElasticityClient::immediateScrollByWithoutContentEdgeConstraints(const gfx::Vector2dF& delta) {
+  stretch_offset_ += delta;
+  // tree_->UpdateRubberband(-stretch_offset_);
+}
+
+void TreeScrollElasticityClient::startSnapRubberbandTimer() {
+  timer_active_ = true;
+  tree_->SetNeedsAnimate();
+}
+
+void TreeScrollElasticityClient::stopSnapRubberbandTimer() {
+  timer_active_ = false;
+}
+
+void TreeScrollElasticityClient::adjustScrollPositionToBoundsIfNecessary() {
+}
+
+}  // namespace cc