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

ui/android/overscroll_refresh.cc

Index: ui/android/overscroll_refresh.cc
diff --git a/ui/android/overscroll_refresh.cc b/ui/android/overscroll_refresh.cc
index 2f2af62d8cd56abe468ecb688e0675fa140b8ccc..546d19d41ba19cb4c0f4a19364b45bdebeb3c330 100644
--- a/ui/android/overscroll_refresh.cc
+++ b/ui/android/overscroll_refresh.cc
@@ -20,16 +20,15 @@ OverscrollRefresh::OverscrollRefresh(OverscrollRefreshHandler* handler)
     : scrolled_to_top_(true),
       overflow_y_hidden_(false),
       scroll_consumption_state_(DISABLED),
-      handler_(handler) {
-  DCHECK(handler);
-}
+      handler_(handler) {}
 
 OverscrollRefresh::~OverscrollRefresh() {
 }
 
 void OverscrollRefresh::Reset() {
   scroll_consumption_state_ = DISABLED;
-  handler_->PullReset();
+  if (handler_)

[boliu, 2017/08/23 19:17:02]

hmm, handler is constant, so if this one needs a null check, then they all need
null checks?

Looks like this is all for testing? In general, tests should not negatively
affect quality of production code. Can you make sure tests passes in a fake
handler here

[sunyunjia, 2017/08/23 23:47:06]

Feels like it's a bit complicated to mock an OverscrollRefreshHandler as its
constructor needs some java object?
For now I created another constructor and restored all the DCHECKs. Please let
me know if you have any suggestions!

+    handler_->PullReset();
 }
 
 void OverscrollRefresh::OnScrollBegin() {
@@ -43,15 +42,11 @@ void OverscrollRefresh::OnScrollEnd(const gfx::Vector2dF& scroll_velocity) {
   Release(allow_activation);
 }
 
-void OverscrollRefresh::OnScrollUpdateAck(bool was_consumed) {
+void OverscrollRefresh::OnOverscrolled() {
   if (scroll_consumption_state_ != AWAITING_SCROLL_UPDATE_ACK)
     return;
 
-  if (was_consumed) {
-    scroll_consumption_state_ = DISABLED;
-    return;
-  }
-
+  DCHECK(handler_);
   scroll_consumption_state_ = handler_->PullStart() ? ENABLED : DISABLED;
 }
 
@@ -68,6 +63,7 @@ bool OverscrollRefresh::WillHandleScrollUpdate(
       return false;
 
     case ENABLED:
+      DCHECK(handler_);
       handler_->PullUpdate(scroll_delta.y());
       return true;
   }
@@ -97,8 +93,10 @@ void OverscrollRefresh::OnFrameUpdated(
 }
 
 void OverscrollRefresh::Release(bool allow_refresh) {
-  if (scroll_consumption_state_ == ENABLED)
+  if (scroll_consumption_state_ == ENABLED) {
+    DCHECK(handler_);
     handler_->PullRelease(allow_refresh);
+  }
   scroll_consumption_state_ = DISABLED;
 }