Replace various ScrollableArea scroll methods with setScrollPosition

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 edd58bd52392b820387fa793d139f5e92d9a2a43..4dde004b38cfdd3eedb4703ec2ffa8caac0dc458 100644
--- a/Source/core/frame/LocalFrame.cpp
+++ b/Source/core/frame/LocalFrame.cpp
@@ -520,7 +520,9 @@ void LocalFrame::setPageAndTextZoomFactors(float pageZoomFactor, float textZoomF
             // Update the scroll position when doing a full page zoom, so the content stays in relatively the same position.
             LayoutPoint scrollPosition = view->scrollPosition();
             float percentDifference = (pageZoomFactor / m_pageZoomFactor);
-            view->setScrollPosition(DoublePoint(scrollPosition.x() * percentDifference, scrollPosition.y() * percentDifference));
+            view->setScrollPosition(
+                DoublePoint(scrollPosition.x() * percentDifference, scrollPosition.y() * percentDifference),
+                ProgrammaticScroll);

[skobes, 2015/06/04 23:35:47]

Why is this a programmatic scroll?  It seems conceptually similar to pinch zoom.

[bokan, 2015/06/05 15:15:23]

I guess it could be argued either way, my view is this (and pinch-zoom actually)
is the browser keeping the view anchored so it's not really the user scrolling.
In this case more so, the user action doesn't really relate to scrolling. i.e.
If the user changes the zoom level, we shouldn't set the FrameView's
scrolledByUser and prevent resetting the scroll offset on a history navigation.

It does fall into an "in between" type though, maybe we want a separate type?
AnchorScroll or something like that? I was already thinking about that since
we'll want to do some special behavior for scrolling in RootFrameViewport if
it's from a pinch-zoom gesture. If you don't feel strongly though I'd leave that
for the RootFrameViewport/pinchzoom patch.

[skobes, 2015/06/05 15:53:57]

It would be nice to have a comment on the ScrollType enum that documents what
the intent and consequences of each value are.  Can be a separate patch.

[bokan, 2015/06/05 20:35:35]

Good point, I'll add it once the rest of my patches land and it's more clear
what the differences are.

         }
     }