Implement CSS: scroll-boundary-behavior

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 65c190f2ef20cc1aa213886b1fa07a9dec33be82..5677bbe7f9c0a36dc3228e12a92b71f8221e56cc 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -23,6 +23,7 @@
 #include "cc/cc_export.h"
 #include "cc/debug/layer_tree_debug_state.h"
 #include "cc/input/input_handler.h"
+#include "cc/input/scroll_boundary_behavior.h"
 #include "cc/layers/draw_mode.h"
 #include "cc/layers/draw_properties.h"
 #include "cc/layers/layer_collections.h"
@@ -291,6 +292,11 @@ class CC_EXPORT LayerImpl {
   gfx::ScrollOffset ClampScrollOffsetToLimits(gfx::ScrollOffset offset) const;
   gfx::Vector2dF ClampScrollToMaxScrollOffset();
 
+  void SetScrollBoundaryBehavior(const ScrollBoundaryBehavior&);
+  ScrollBoundaryBehavior scroll_boundary_behavior() {
+    return scroll_boundary_behavior_;

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

Does LayerImpl need to have a copy of this value, or is it enough for ScrollNode
to have it? If it's needed just for tests, it can be moved to
LayerImplTestProperties.

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

Done.

+  }
+
   // Returns the delta of the scroll that was outside of the bounds of the
   // initial scroll
   gfx::Vector2dF ScrollBy(const gfx::Vector2dF& scroll);
@@ -565,6 +571,8 @@ class CC_EXPORT LayerImpl {
 
   bool has_transform_node_ : 1;
 
+  ScrollBoundaryBehavior scroll_boundary_behavior_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };