Fix issue with non-touchpad scrolling event over resizer: should not cause an area resize.

third_party/WebKit/Source/core/input/ScrollManager.cpp

Index: third_party/WebKit/Source/core/input/ScrollManager.cpp
diff --git a/third_party/WebKit/Source/core/input/ScrollManager.cpp b/third_party/WebKit/Source/core/input/ScrollManager.cpp
index a10cea7fb3b7ce8bcd106cfe332ba7f95b36513a..d0d2bb9dcbc7db5ce681f1974a7ce32c1c9f3516 100644
--- a/third_party/WebKit/Source/core/input/ScrollManager.cpp
+++ b/third_party/WebKit/Source/core/input/ScrollManager.cpp
@@ -433,6 +433,9 @@ bool ScrollManager::isScrollbarHandlingGestures() const
 
 bool ScrollManager::handleScrollGestureOnResizer(Node* eventTarget, const PlatformGestureEvent& gestureEvent)
 {
+    if (gestureEvent.source() != PlatformGestureSourceTouchscreen)
+        return false;
+
     if (gestureEvent.type() == PlatformEvent::GestureScrollBegin) {
         PaintLayer* layer = eventTarget->layoutObject() ? eventTarget->layoutObject()->enclosingLayer() : nullptr;
         IntPoint p = m_frame->view()->rootFrameToContents(gestureEvent.position());