OverscrollGlow for mainThread-{BLINK CHANGES}

Source/core/frame/LocalFrame.cpp

Index: Source/core/frame/LocalFrame.cpp
diff --git a/Source/core/frame/LocalFrame.cpp b/Source/core/frame/LocalFrame.cpp
index 5b711fc47e11e041234ce5b1493ea2468f11f840..938814d49ae4884e0ab629fe66a985fb47f16c79 100644
--- a/Source/core/frame/LocalFrame.cpp
+++ b/Source/core/frame/LocalFrame.cpp
@@ -713,21 +713,20 @@ void LocalFrame::removeSpellingMarkersUnderWords(const Vector<String>& words)
     spellChecker().removeSpellingMarkersUnderWords(words);
 }
 
-static bool scrollAreaOnBothAxes(const FloatSize& delta, ScrollableArea& view)
+static ScrollResult scrollAreaOnBothAxes(const FloatSize& delta, ScrollableArea& view)
 {
-    bool scrolledHorizontal = view.scroll(ScrollLeft, ScrollByPrecisePixel, delta.width());
-    bool scrolledVertical = view.scroll(ScrollUp, ScrollByPrecisePixel, delta.height());
-    return scrolledHorizontal || scrolledVertical;
+    ScrollResultOneDimensional horizontal = view.scroll(ScrollLeft, ScrollByPrecisePixel, delta.width());
+    ScrollResultOneDimensional vertical = view.scroll(ScrollUp, ScrollByPrecisePixel, delta.height());
+    return ScrollResult(horizontal.didScroll, vertical.didScroll, view.scrollSize(HorizontalScrollbar) ? horizontal.unusedScrollDelta : 0.0f, view.scrollSize(VerticalScrollbar) ? vertical.unusedScrollDelta : 0.0f);

[majidvp, 2015/06/03 12:09:46]

Using scrollSize to detect scrollability is reasonable but I don't think we
should be adjusting (mis-reporting) unused delta here to fix the overscroll
issue elsewhere. I prefer to keep the overscroll related logic local to
EventHandler.

 }
 
-// Returns true if a scroll occurred.
-bool LocalFrame::applyScrollDelta(const FloatSize& delta, bool isScrollBegin)
+ScrollResult LocalFrame::applyScrollDelta(const FloatSize& delta, bool isScrollBegin)
 {
     if (isScrollBegin)
         host()->topControls().scrollBegin();
 
     if (!view() || delta.isZero())
-        return false;
+        return ScrollResult(false, false, delta.width(), delta.height());
 
     FloatSize remainingDelta = delta;
 
@@ -736,14 +735,12 @@ bool LocalFrame::applyScrollDelta(const FloatSize& delta, bool isScrollBegin)
         remainingDelta = host()->topControls().scrollBy(remainingDelta);
 
     if (remainingDelta.isZero())
-        return true;
-
-    bool consumed = remainingDelta != delta;
-
-    if (scrollAreaOnBothAxes(remainingDelta, *view()->scrollableArea()))
-        return true;
+        return ScrollResult(delta.width(), delta.height(), 0.0f, 0.0f);
 
-    return consumed;
+    ScrollResult result = scrollAreaOnBothAxes(remainingDelta, *view()->scrollableArea());
+    result.didScrollX = result.didScrollX || (remainingDelta.width() != delta.width());
+    result.didScrollY = result.didScrollY || (remainingDelta.height() != delta.height());
+    return result;
 }
 
 bool LocalFrame::shouldScrollTopControls(const FloatSize& delta) const