Removed main-thread one dimensional scrolling paths.

third_party/WebKit/Source/core/frame/LocalFrame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 757 matching lines @@
 bool LocalFrame::shouldReuseDefaultView(const KURL& url) const
 {
     return loader().stateMachine()->isDisplayingInitialEmptyDocument() && document()->isSecureTransitionTo(url);
 }
 
 void LocalFrame::removeSpellingMarkersUnderWords(const Vector<String>& words)
 {
     spellChecker().removeSpellingMarkersUnderWords(words);
 }
 
-static ScrollResult scrollAreaOnBothAxes(ScrollGranularity granularity, const FloatSize& delta, ScrollableArea& view)
-{
-    ScrollResultOneDimensional scrolledHorizontal = view.userScroll(ScrollLeft, granularity, delta.width());
-    ScrollResultOneDimensional scrolledVertical = view.userScroll(ScrollUp, granularity, delta.height());
-    return ScrollResult(scrolledHorizontal.didScroll, scrolledVertical.didScroll, scrolledHorizontal.unusedScrollDelta, scrolledVertical.unusedScrollDelta);
-}
-
 // Returns true if a scroll occurred.
 ScrollResult LocalFrame::applyScrollDelta(ScrollGranularity granularity, const FloatSize& delta, bool isScrollBegin)
 {
     if (isScrollBegin)
         host()->topControls().scrollBegin();
 
     if (!view() || delta.isZero())
         return ScrollResult(false, false, delta.width(), delta.height());
 
     FloatSize remainingDelta = delta;
 
     // If this is main frame, allow top controls to scroll first.
     if (shouldScrollTopControls(delta))
         remainingDelta = host()->topControls().scrollBy(remainingDelta);
 
     if (remainingDelta.isZero())
         return ScrollResult(delta.width(), delta.height(), 0.0f, 0.0f);
 
-    ScrollResult result = scrollAreaOnBothAxes(granularity, remainingDelta, *view()->scrollableArea());
+    // TODO(bokan): The delta coming in here is the GSU event delta, which is

[skobes, 2016/02/29 18:52:47]

what is GSU?

[bokan, 2016/03/01 05:56:24]

Sorry, forgot not everyone works on input :) (Gesture Scroll Update).

I've updated the wording.

+    // positive if the user scrolls up. For scrolling, a positive delta implies

[tdresser, 2016/02/29 14:53:43]

positive if the user scrolls up or left

[bokan, 2016/03/01 05:56:24]

Done.

+    // downward scrolling. This negation should happen up in the call chain.
+    FloatSize normalizedDelta = remainingDelta.scaledBy(-1);
+
+    ScrollResult result = view()->scrollableArea()->userScroll(granularity, normalizedDelta);
+
     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
 {
     if (!isMainFrame())
         return false;
@@ skipping 74 matching lines @@
 {
     m_frame->disableNavigation();
 }
 
 FrameNavigationDisabler::~FrameNavigationDisabler()
 {
     m_frame->enableNavigation();
 }
 
 } // namespace blink