Allow objects without scrollbars to be scrollable

Source/core/platform/ScrollView.cpp

Index: Source/core/platform/ScrollView.cpp
diff --git a/Source/core/platform/ScrollView.cpp b/Source/core/platform/ScrollView.cpp
index 67382df3ce5fa01bef3a3f530315221e5d5ff54f..4e63f66e5f178cc01f946f1abcebbb4ae81a9529 100644
--- a/Source/core/platform/ScrollView.cpp
+++ b/Source/core/platform/ScrollView.cpp
@@ -43,7 +43,6 @@ ScrollView::ScrollView()
     , m_verticalScrollbarMode(ScrollbarAuto)
     , m_horizontalScrollbarLock(false)
     , m_verticalScrollbarLock(false)
-    , m_prohibitsScrolling(false)
     , m_canBlitOnScroll(true)
     , m_scrollbarsAvoidingResizer(0)
     , m_scrollbarsSuppressed(false)
@@ -284,15 +283,16 @@ IntPoint ScrollView::adjustScrollPositionWithinRange(const IntPoint& scrollPoint
 
 int ScrollView::scrollSize(ScrollbarOrientation orientation) const
 {
+    Scrollbar* scrollbar = ((orientation == HorizontalScrollbar) ? m_horizontalScrollbar : m_verticalScrollbar).get();
+
     // If no scrollbars are present, it does not indicate content is not be scrollable.
-    if (!m_horizontalScrollbar && !m_verticalScrollbar && !prohibitsScrolling()) {
+    if (!scrollbar) {
         IntSize scrollSize = m_contentsSize - visibleContentRect().size();
         scrollSize.clampNegativeToZero();
         return orientation == HorizontalScrollbar ? scrollSize.width() : scrollSize.height();
     }
 
-    Scrollbar* scrollbar = ((orientation == HorizontalScrollbar) ? m_horizontalScrollbar : m_verticalScrollbar).get();
-    return scrollbar ? (scrollbar->totalSize() - scrollbar->visibleSize()) : 0;
+    return scrollbar->totalSize() - scrollbar->visibleSize();
 }
 
 void ScrollView::notifyPageThatContentAreaWillPaint() const
@@ -330,9 +330,6 @@ int ScrollView::scrollPosition(Scrollbar* scrollbar) const
 
 void ScrollView::setScrollPosition(const IntPoint& scrollPoint)
 {
-    if (prohibitsScrolling())
-        return;
-
     IntPoint newScrollPosition = adjustScrollPositionWithinRange(scrollPoint);
 
     if (newScrollPosition == scrollPosition())
@@ -374,7 +371,7 @@ static const unsigned cMaxUpdateScrollbarsPass = 2;
 
 void ScrollView::updateScrollbars(const IntSize& desiredOffset)
 {
-    if (m_inUpdateScrollbars || prohibitsScrolling())
+    if (m_inUpdateScrollbars)
         return;
 
     // If we came in here with the view already needing a layout, then go ahead and do that
@@ -484,7 +481,6 @@ void ScrollView::updateScrollbars(const IntSize& desiredOffset)
 
     if (m_horizontalScrollbar) {
         int clientWidth = visibleWidth();
-        int pageStep = max(max<int>(clientWidth * Scrollbar::minFractionToStepWhenPaging(), clientWidth - Scrollbar::maxOverlapBetweenPages()), 1);
         IntRect oldRect(m_horizontalScrollbar->frameRect());
         IntRect hBarRect(0,
                         height() - m_horizontalScrollbar->height(),
@@ -497,7 +493,6 @@ void ScrollView::updateScrollbars(const IntSize& desiredOffset)
         if (m_scrollbarsSuppressed)
             m_horizontalScrollbar->setSuppressInvalidation(true);
         m_horizontalScrollbar->setEnabled(contentsWidth() > clientWidth);
-        m_horizontalScrollbar->setSteps(Scrollbar::pixelsPerLineStep(), pageStep);
         m_horizontalScrollbar->setProportion(clientWidth, contentsWidth());
         if (m_scrollbarsSuppressed)
             m_horizontalScrollbar->setSuppressInvalidation(false); 
@@ -505,7 +500,6 @@ void ScrollView::updateScrollbars(const IntSize& desiredOffset)
 
     if (m_verticalScrollbar) {
         int clientHeight = visibleHeight();
-        int pageStep = max(max<int>(clientHeight * Scrollbar::minFractionToStepWhenPaging(), clientHeight - Scrollbar::maxOverlapBetweenPages()), 1);
         IntRect oldRect(m_verticalScrollbar->frameRect());
         IntRect vBarRect(width() - m_verticalScrollbar->width(), 
                          0,
@@ -518,7 +512,6 @@ void ScrollView::updateScrollbars(const IntSize& desiredOffset)
         if (m_scrollbarsSuppressed)
             m_verticalScrollbar->setSuppressInvalidation(true);
         m_verticalScrollbar->setEnabled(contentsHeight() > clientHeight);
-        m_verticalScrollbar->setSteps(Scrollbar::pixelsPerLineStep(), pageStep);
         m_verticalScrollbar->setProportion(clientHeight, contentsHeight());
         if (m_scrollbarsSuppressed)
             m_verticalScrollbar->setSuppressInvalidation(false);
@@ -822,6 +815,14 @@ void ScrollView::positionScrollbarLayers()
     positionScrollCornerLayer(layerForScrollCorner(), scrollCornerRect());
 }
 
+bool ScrollView::userInputScrollable(ScrollbarOrientation orientation) const
+{
+    ScrollbarMode mode = (orientation == HorizontalScrollbar) ?
+        m_horizontalScrollbarMode : m_verticalScrollbarMode;
+
+    return mode == ScrollbarAuto || mode == ScrollbarAlwaysOn;
+}
+
 void ScrollView::repaintContentRectangle(const IntRect& rect)
 {
     IntRect paintRect = rect;