Add metric to know how user use scrollbar

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 253 matching lines @@
                                           : nullptr);
   m_visuallyNonEmptyCharacterCount = 0;
   m_visuallyNonEmptyPixelCount = 0;
   m_isVisuallyNonEmpty = false;
   m_mainThreadScrollingReasons = 0;
   m_layoutObjectCounter.reset();
   clearFragmentAnchor();
   m_viewportConstrainedObjects.reset();
   m_layoutSubtreeRootList.clear();
   m_orthogonalWritingModeRootList.clear();
+  m_sentScrollbarUseUMA.reset();
 }
 
 // Call function for each non-throttled frame view in pre tree order.
 // Note it needs a null check of the frame's layoutView to access it in case of
 // detached frames.
 template <typename Function>
 void FrameView::forAllNonThrottledFrameViews(const Function& function) {
   if (shouldThrottleRendering())
     return;
 
@@ skipping 3466 matching lines @@
 
   if (!layerForScrolling())
     return;
   WebLayer* layer = layerForScrolling()->platformLayer();
   if (!layer)
     return;
   layer->setUserScrollable(userInputScrollable(HorizontalScrollbar),
                            userInputScrollable(VerticalScrollbar));
 }
 
+bool FrameView::shouldSendScrollbarUseUMA(int part) {
+  if (m_sentScrollbarUseUMA[part])
+    return false;
+  m_sentScrollbarUseUMA[part] = true;
+  return true;
+}
+
 IntSize FrameView::visibleContentSize(
     IncludeScrollbarsInRect scrollbarInclusion) const {
   return scrollbarInclusion == ExcludeScrollbars
              ? excludeScrollbars(frameRect().size())
              : frameRect().size();
 }
 
 IntRect FrameView::visibleContentRect(
     IncludeScrollbarsInRect scrollbarInclusion) const {
   return IntRect(IntPoint(flooredIntSize(m_scrollOffset)),
@@ skipping 1216 matching lines @@
   // This is the top-level frame, so no mapping necessary.
   if (m_frame->isMainFrame())
     return;
 
   LayoutRect viewportIntersectionRect(remoteViewportIntersection());
   transformState.move(
       LayoutSize(-viewportIntersectionRect.x(), -viewportIntersectionRect.y()));
 }
 
 }  // namespace blink