[not for review - epic CL] Adding Elastic+Momentum+Layered scrolling to views::ScrollView

ui/compositor/layer.cc

 // Copyright (c) 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 "ui/compositor/layer.h"
 
 #include <algorithm>
 #include <memory>
 #include <utility>
 
@@ skipping 510 matching lines @@
 bool Layer::HasPendingThreadedAnimationsForTesting() const {
   return animator_->HasPendingThreadedAnimationsForTesting();
 }
 
 void Layer::SwitchCCLayerForTest() {
   scoped_refptr<cc::Layer> new_layer = cc::PictureLayer::Create(this);
   SwitchToLayer(new_layer);
   content_layer_ = new_layer;
 }
 
+gfx::ScrollOffset Layer::CurrentScrollOffset() const {
+  const Compositor* compositor = GetCompositor();
+  if (compositor)
+    return compositor->GetScrollOffsetForLayer(cc_layer_->id());
+  return cc_layer_->scroll_offset();
+}
+
+void Layer::SetScrollOffset(const gfx::ScrollOffset& offset) {
+  Compositor* compositor = GetCompositor();
+  bool scrolled_on_impl_side =
+      compositor && compositor->ScrollLayerTo(cc_layer_->id(), offset);
+
+  if (!scrolled_on_impl_side)
+    cc_layer_->SetScrollOffset(offset);
+
+  DCHECK_EQ(offset.x(), CurrentScrollOffset().x());
+  DCHECK_EQ(offset.y(), CurrentScrollOffset().y());
+}
+
+void Layer::SetScrollable(Layer* parent_clip_layer,
+                          bool can_overscroll,
+                          const base::Closure& on_scroll) {
+  cc_layer_->SetScrollParent(parent_clip_layer->cc_layer_);
+  cc_layer_->SetIsContainerForFixedPositionLayers(true);
+  cc_layer_->SetScrollClipAndCanOverscroll(parent_clip_layer->cc_layer_->id(),
+                                           can_overscroll);
+  cc_layer_->set_did_scroll_callback(on_scroll);
+  cc_layer_->SetUserScrollable(true, true);
+}
+
 void Layer::SetTextureMailbox(
     const cc::TextureMailbox& mailbox,
     std::unique_ptr<cc::SingleReleaseCallback> release_callback,
     gfx::Size texture_size_in_dip) {
   DCHECK(type_ == LAYER_TEXTURED || type_ == LAYER_SOLID_COLOR);
   DCHECK(mailbox.IsValid());
   DCHECK(release_callback);
   if (!texture_layer_.get()) {
     scoped_refptr<cc::TextureLayer> new_layer =
         cc::TextureLayer::CreateForMailbox(this);
@@ skipping 526 matching lines @@
   if (animator_) {
     animator_->ResetCompositor(compositor);
     animator_->RemoveFromCollection(collection);
   }
 
   for (auto* child : children_)
     child->ResetCompositorForAnimatorsInTree(compositor);
 }
 
 }  // namespace ui