Fix drag-and-drop autoscrolling with --enable-pinch-virtual-viewport

Source/core/frame/PinchViewport.cpp

Index: Source/core/frame/PinchViewport.cpp
diff --git a/Source/core/frame/PinchViewport.cpp b/Source/core/frame/PinchViewport.cpp
index ffe9f13419e98bfa2b79f3f1c4845bf13718bfce..39c250f02d7619beeab8ce7c778540acd18f3c97 100644
--- a/Source/core/frame/PinchViewport.cpp
+++ b/Source/core/frame/PinchViewport.cpp
@@ -149,15 +149,18 @@ void PinchViewport::scrollIntoView(const LayoutRect& rect)
 
     FrameView* view = mainFrame()->view();
 
-    // Snap the visible rect to layout units to match the input rect.
-    FloatRect visible = LayoutRect(visibleRect());
+    // Snap the visible rect to layout units to match the input rect. Intersect
+    // with the FrameView so that we exclude scrollbars from the visible area.
+    FloatRect visible = intersection(
+        LayoutRect(visibleRectInDocument()),
+        LayoutRect(view->visibleContentRect()));
 
     float centeringOffsetX = (visible.width() - rect.width()) / 2;
     float centeringOffsetY = (visible.height() - rect.height()) / 2;
 
     DoublePoint targetOffset(
-        rect.x() - centeringOffsetX - visible.x(),
-        rect.y() - centeringOffsetY - visible.y());

[bokan, 2015/01/15 23:53:01]

visibleRect() is relative to the FrameView, since we now use
visibleRectInDocument, the adjustment here is no longer necessary.

+        rect.x() - centeringOffsetX,
+        rect.y() - centeringOffsetY);
 
     view->setScrollPosition(targetOffset);