Implement CSS: scroll-boundary-behavior

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 21f7f0d4e4849ef987475bb891dbf2d71712308b..c5cc08dc661467efcd1c4d9b766177001b06effa 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -65,7 +65,9 @@ Layer::Inputs::Inputs(int layer_id)
       clip_parent(nullptr),
       has_will_change_transform_hint(false),
       hide_layer_and_subtree(false),
-      client(nullptr) {}
+      client(nullptr),
+      scroll_boundary_behavior(
+          ScrollBoundaryBehavior::kScrollBoundaryBehaviorTypeAuto) {}
 
 Layer::Inputs::~Inputs() {}
 
@@ -306,6 +308,14 @@ void Layer::SetBounds(const gfx::Size& size) {
   SetNeedsCommit();
 }
 
+void Layer::SetScrollBoundaryBehavior(const ScrollBoundaryBehavior& behavior) {
+  if (scroll_boundary_behavior() == behavior)
+    return;
+  inputs_.scroll_boundary_behavior = behavior;

[ajuma, 2017/06/30 20:46:49]

This also needs to update the scroll node if there is one, and otherwise trigger
a property tree rebuild (see SetUserScrollable for an example of this).

[sunyunjia, 2017/07/14 02:59:00]

Done.

+
+  SetNeedsCommit();
+}
+
 Layer* Layer::RootLayer() {
   Layer* layer = this;
   while (layer->parent())
@@ -1204,6 +1214,7 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   layer->SetUpdateRect(inputs_.update_rect);
 
   layer->SetHasWillChangeTransformHint(has_will_change_transform_hint());
+  layer->SetScrollBoundaryBehavior(inputs_.scroll_boundary_behavior);
   layer->SetNeedsPushProperties();
 
   // Reset any state that should be cleared for the next update.