Use scroll-boundary-behavior to control overscroll-refresh/glow on android.

third_party/WebKit/Source/core/input/ScrollManager.cpp

 // Copyright 2016 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 "core/input/ScrollManager.h"
 
 #include <memory>
 #include "core/dom/DOMNodeIds.h"
 #include "core/dom/NodeComputedStyle.h"
 #include "core/events/GestureEvent.h"
@@ skipping 69 matching lines @@
 }
 
 AutoscrollController* ScrollManager::GetAutoscrollController() const {
   if (Page* page = frame_->GetPage())
     return &page->GetAutoscrollController();
   return nullptr;
 }
 
 static bool CanPropagate(const ScrollState& scroll_state,
                          const Element& element) {
+  if (!element.GetLayoutBox()->GetScrollableArea())

[chrishtr, 2017/08/25 20:55:06]

Why did you need to change this?

[sunyunjia, 2017/08/25 21:19:44]

This is a bug in the previous patch--the scroll-chaining part of
scroll-boundary-behavior. We would like the scroll-boundary-behavior affects
only the scrollable containers, not all the elements.

Specifically, if the body has scroll-boundary-behavior: contain, and it hasn't
been added to the scroll-chain because it's not scrollable, the scroll-chain
would be cut from that point. Then the overscroll message won't be generated at
all, because it is only generated at the rootscroller level, which is the
document. And we won't have the glow-effect we would still like to see with the
value "contain"

We don't need this check at cc side, because for now, cc handles overscroll
outside the scroll-chain. Cutting scroll-chain early won't affect overscroll.
See crbug.com/755164 .

You can find the discussion at
message143(https://codereview.chromium.org/2884423003/#msg143) and
message152(https://codereview.chromium.org/2884423003/#msg152)

+    return true;
+
   return (scroll_state.deltaXHint() == 0 ||
           element.GetComputedStyle()->ScrollBoundaryBehaviorX() ==
               EScrollBoundaryBehavior::kAuto) &&
          (scroll_state.deltaYHint() == 0 ||
           element.GetComputedStyle()->ScrollBoundaryBehaviorY() ==
               EScrollBoundaryBehavior::kAuto);
 }
 
 void ScrollManager::RecomputeScrollChain(const Node& start_node,
                                          const ScrollState& scroll_state,
@@ skipping 613 matching lines @@
                                 &should_update_capture)) {
       if (should_update_capture)
         scrollbar_handling_scroll_gesture_ = scrollbar;
       return true;
     }
   }
   return false;
 }
 
 }  // namespace blink