Eliminate drag-off-end scroll canceling for Linux.

content/renderer/webscrollbarbehavior_impl_gtkoraura.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/webscrollbarbehavior_impl_gtkoraura.h"
 
 #include "third_party/WebKit/public/platform/WebPoint.h"
 #include "third_party/WebKit/public/platform/WebRect.h"
 
 namespace content {
@@ skipping 22 matching lines @@
   static const int kOffSideMultiplier = 8;
 
   // Find the rect within which we shouldn't snap, by expanding the track rect
   // in both dimensions.
   gfx::Rect noSnapRect(scrollbarRect);
   const int thickness = isHorizontal ? noSnapRect.height() : noSnapRect.width();
   noSnapRect.Inset(
       (isHorizontal ? kOffEndMultiplier : kOffSideMultiplier) * -thickness,
       (isHorizontal ? kOffSideMultiplier : kOffEndMultiplier) * -thickness);
 
-  // We should snap iff the event is outside our calculated rect.
+  // On most platforms, we should snap iff the event is outside our calculated
+  // rect.  On Linux, however, we should not snap for events off the ends, but
+  // not the sides, of the rect.
+#if (defined(OS_LINUX) && !defined(OS_CHROMEOS))
+  return isHorizontal ?
+      (eventPoint.y < noSnapRect.y() || eventPoint.y >= noSnapRect.bottom()) :
+      (eventPoint.x < noSnapRect.x() || eventPoint.x >= noSnapRect.right());
+#else
   return !noSnapRect.Contains(eventPoint);
+#endif
 }
 
 }  // namespace content