Implement CSS: scroll-boundary-behavior

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index af710a5670f2b3475c8303f1f71f48bc76d84b35..34e34df6d64fb1d5768382103a1d7d8a4c96adbe 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -528,8 +528,9 @@ void Element::NativeDistributeScroll(ScrollState& scroll_state) {
 
   CallApplyScroll(scroll_state);
 
-  if (delta_x != scroll_state.deltaX() || delta_y != scroll_state.deltaY())
+  if (delta_x != scroll_state.deltaX() || delta_y != scroll_state.deltaY()) {
     scroll_state.SetCurrentNativeScrollingElement(this);
+  }

[bokan, 2017/05/19 19:35:57]

Nit: no braces

[sunyunjia, 2017/05/25 20:07:10]

Done.

 }
 
 void Element::CallDistributeScroll(ScrollState& scroll_state) {
@@ -593,8 +594,17 @@ void Element::NativeApplyScroll(ScrollState& scroll_state) {
                                         scroll_state.deltaGranularity())),
                                     delta);
 
-  if (!result.DidScroll())
+  if (!result.DidScroll()) {
+    if (GetComputedStyle()->ScrollBoundaryBehaviorX() !=

[bokan, 2017/05/19 19:35:57]

Similarly, this should be done at the time that we compute the scroll chain in
ScrollManager::RecomputeScrollChain

[sunyunjia, 2017/05/25 20:07:10]

Done.

+            EScrollBoundaryBehavior::kAuto &&
+        std::abs(delta.Width()) > std::abs(delta.Height()))
+      scroll_state.ConsumeDeltaNative(delta.Width(), 0);
+    if (GetComputedStyle()->ScrollBoundaryBehaviorY() !=
+            EScrollBoundaryBehavior::kAuto &&
+        std::abs(delta.Height()) > std::abs(delta.Width()))
+      scroll_state.ConsumeDeltaNative(0, delta.Height());
     return;
+  }
 
   // FIXME: Native scrollers should only consume the scroll they
   // apply. See crbug.com/457765.