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

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

 // Copyright 2016 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 "core/input/ScrollManager.h"
 
 #include "core/dom/DOMNodeIds.h"
 #include "core/events/GestureEvent.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
@@ skipping 415 matching lines @@
     }
 }
 
 bool ScrollManager::isScrollbarHandlingGestures() const
 {
     return m_scrollbarHandlingScrollGesture.get();
 }
 
 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());
         if (layer && layer->getScrollableArea() && layer->getScrollableArea()->isPointInResizeControl(p, ResizerForTouch)) {
             m_resizeScrollableArea = layer->getScrollableArea();
             m_resizeScrollableArea->setInResizeMode(true);
             m_offsetFromResizeCorner = LayoutSize(m_resizeScrollableArea->offsetFromResizeCorner(p));
             return true;
         }
     } else if (gestureEvent.type() == PlatformEvent::GestureScrollUpdate) {
@@ skipping 57 matching lines @@
 DEFINE_TRACE(ScrollManager)
 {
     visitor->trace(m_frame);
     visitor->trace(m_scrollGestureHandlingNode);
     visitor->trace(m_previousGestureScrolledNode);
     visitor->trace(m_scrollbarHandlingScrollGesture);
     visitor->trace(m_resizeScrollableArea);
 }
 
 } // namespace blink