Refine tap disambiguation UMA to track same-node/different-node.

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 838 matching lines @@
           Vector<IntRect> goodTargets;
           HeapVector<Member<Node>> highlightNodes;
           findGoodTouchTargets(boundingBox, mainFrameImpl()->frame(),
                                goodTargets, highlightNodes);
           // FIXME: replace touch adjustment code when numberOfGoodTargets == 1?
           // Single candidate case is currently handled by:
           // https://bugs.webkit.org/show_bug.cgi?id=85101
           if (goodTargets.size() >= 2 && m_client &&
               m_client->didTapMultipleTargets(visualViewportOffset, boundingBox,
                                               goodTargets)) {
+            // Stash the position of the node that would've been used absent
+            // disambiguation, for UMA purposes.
+            m_lastTapDisambiguationBestCandidatePosition =
+                targetedEvent.hitTestResult().roundedPointInMainFrame() -
+                roundedIntSize(targetedEvent.hitTestResult().localPoint());
+
             enableTapHighlights(highlightNodes);
             for (size_t i = 0; i < m_linkHighlights.size(); ++i)
               m_linkHighlights[i]->startHighlightAnimationIfNeeded();
             eventResult = WebInputEventResult::HandledSystem;
             eventCancelled = true;
             break;
           }
         }
       }
 
@@ skipping 55 matching lines @@
       eventResult = mainFrameImpl()->frame()->eventHandler().handleGestureEvent(
           targetedEvent);
       break;
     }
     default: { NOTREACHED(); }
   }
   m_client->didHandleGestureEvent(event, eventCancelled);
   return eventResult;
 }
 
+namespace {
+// This enum is used to back a histogram, and should therefore be treated as
+// append-only.
+enum TapDisambiguationResult {
+  UmaTapDisambiguationOther = 0,
+  UmaTapDisambiguationBackButton = 1,
+  UmaTapDisambiguationTappedOutside = 2,
+  UmaTapDisambiguationTappedInsideDeprecated = 3,
+  UmaTapDisambiguationTappedInsideSameNode = 4,
+  UmaTapDisambiguationTappedInsideDifferentNode = 5,
+  UmaTapDisambiguationCount = 6,
+};
+
+void RecordTapDisambiguation(TapDisambiguationResult result) {
+  UMA_HISTOGRAM_ENUMERATION("Touchscreen.TapDisambiguation", result,
+                            UmaTapDisambiguationCount);
+}
+
+}  // namespace
+
+void WebViewImpl::resolveTapDisambiguation(double timestampSeconds,
+                                           WebPoint tapViewportOffset,
+                                           bool isLongPress) {
+  WebGestureEvent event(
+      isLongPress ? WebInputEvent::GestureLongPress : WebInputEvent::GestureTap,
+      WebInputEvent::NoModifiers, timestampSeconds);
+
+  event.x = tapViewportOffset.x;
+  event.y = tapViewportOffset.y;
+  event.sourceDevice = blink::WebGestureDeviceTouchscreen;
+
+  {
+    // Compute UMA stat about whether the node selected by disambiguation UI was
+    // different from the one preferred by the regular hit-testing + adjustment
+    // logic.
+    WebGestureEvent scaledEvent =
+        TransformWebGestureEvent(mainFrameImpl()->frameView(), event);
+    GestureEventWithHitTestResults targetedEvent =
+        m_page->deprecatedLocalMainFrame()->eventHandler().targetGestureEvent(
+            scaledEvent);
+    WebPoint nodePosition =
+        targetedEvent.hitTestResult().roundedPointInMainFrame() -
+        roundedIntSize(targetedEvent.hitTestResult().localPoint());
+    TapDisambiguationResult result =
+        (nodePosition == m_lastTapDisambiguationBestCandidatePosition)
+            ? UmaTapDisambiguationTappedInsideSameNode
+            : UmaTapDisambiguationTappedInsideDifferentNode;
+    RecordTapDisambiguation(result);
+  }
+
+  handleGestureEvent(event);
+}
+
 WebInputEventResult WebViewImpl::handleSyntheticWheelFromTouchpadPinchEvent(
     const WebGestureEvent& pinchEvent) {
   DCHECK_EQ(pinchEvent.type(), WebInputEvent::GesturePinchUpdate);
 
   // For pinch gesture events, match typical trackpad behavior on Windows by
   // sending fake wheel events with the ctrl modifier set when we see trackpad
   // pinch gestures.  Ideally we'd someday get a platform 'pinch' event and
   // send that instead.
   WebMouseWheelEvent wheelEvent(
       WebInputEvent::MouseWheel,
@@ skipping 3233 matching lines @@
   if (focusedFrame->localFrameRoot() != mainFrameImpl()->frame())
     return nullptr;
   return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const {
   return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink