ScrollableArea::pixelsPerLine should return viewport pixels in use-zoom-for-dsf mode

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

 /*
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 55 matching lines @@
 // problematic non-Oilpan as the type expands to DummyBase, exporting it
 // also from 'platform' as a result. Bringing about duplicate DummyBases
 // as core also exports same; with component build linking fails as a
 // result. Hence the workaround of not using a transition type.
 class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin {
 #else
 class PLATFORM_EXPORT ScrollableArea {
 #endif
     WTF_MAKE_NONCOPYABLE(ScrollableArea);
 public:
-    static int pixelsPerLineStep();
+    static int pixelsPerLineStep(HostWindow*);
     static float minFractionToStepWhenPaging();
     static int maxOverlapBetweenPages();
 
     // Convert a non-finite scroll value (Infinity, -Infinity, NaN) to 0 as
     // per http://dev.w3.org/csswg/cssom-view/#normalize-non_finite-values.
     static double normalizeNonFiniteScroll(double value) { return std::isfinite(value) ? value : 0.0; }
 
     // The window that hosts the ScrollableArea. The ScrollableArea will communicate scrolls and repaints to the
     // host window in the window's coordinate space.
     virtual HostWindow* hostWindow() const { return 0; }
@@ skipping 271 matching lines @@
     // vertical-lr / ltr            NO                      NO
     // vertical-lr / rtl            NO                      YES
     // vertical-rl / ltr            YES                     NO
     // vertical-rl / rtl            YES                     YES
     IntPoint m_scrollOrigin;
 };
 
 } // namespace blink
 
 #endif // ScrollableArea_h