Make first TouchStart and first TouchMove events on a flinging layer non-blocking

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

Index: third_party/WebKit/Source/core/input/TouchEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/TouchEventManager.cpp b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
index 597100315230e4647231157628744570e5205f5c..e8008c0f0c2c02a411db291927069be3de96ba2c 100644
--- a/third_party/WebKit/Source/core/input/TouchEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
@@ -192,31 +192,35 @@ WebInputEventResult TouchEventManager::dispatchTouchEvents(
 
             // Only report for top level documents with a single touch on
             // touch-start or the first touch-move.
-            if (touchStartOrFirstTouchMove && touchInfos.size() == 1 && event.cancelable() && m_frame->isMainFrame()) {
+            if (touchStartOrFirstTouchMove && touchInfos.size() == 1 && m_frame->isMainFrame()) {
 
                 // Record the disposition and latency of touch starts and first touch moves before and after the page is fully loaded respectively.
                 int64_t latencyInMicros = static_cast<int64_t>((monotonicallyIncreasingTime() - event.timestamp()) * 1000000.0);
-                if (m_frame->document()->isLoadCompleted()) {
-                    DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsAfterPageLoadHistogram, ("Event.Touch.TouchDispositionsAfterPageLoad", TouchEventDispatchResultTypeMax));
-                    touchDispositionsAfterPageLoadHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? HandledTouches : UnhandledTouches);
+                if (event.cancelable()) {
+                    if (m_frame->document()->isLoadCompleted()) {
+                        DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsAfterPageLoadHistogram, ("Event.Touch.TouchDispositionsAfterPageLoad", TouchEventDispatchResultTypeMax));
+                        touchDispositionsAfterPageLoadHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? HandledTouches : UnhandledTouches);
 
-                    DEFINE_STATIC_LOCAL(CustomCountHistogram, eventLatencyAfterPageLoadHistogram, ("Event.Touch.TouchLatencyAfterPageLoad", 1, 100000000, 50));
-                    eventLatencyAfterPageLoadHistogram.count(latencyInMicros);
-                } else {
-                    DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsBeforePageLoadHistogram, ("Event.Touch.TouchDispositionsBeforePageLoad", TouchEventDispatchResultTypeMax));
-                    touchDispositionsBeforePageLoadHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? HandledTouches : UnhandledTouches);
+                        DEFINE_STATIC_LOCAL(CustomCountHistogram, eventLatencyAfterPageLoadHistogram, ("Event.Touch.TouchLatencyAfterPageLoad", 1, 100000000, 50));
+                        eventLatencyAfterPageLoadHistogram.count(latencyInMicros);
+                    } else {
+                        DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsBeforePageLoadHistogram, ("Event.Touch.TouchDispositionsBeforePageLoad", TouchEventDispatchResultTypeMax));
+                        touchDispositionsBeforePageLoadHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? HandledTouches : UnhandledTouches);
 
-                    DEFINE_STATIC_LOCAL(CustomCountHistogram, eventLatencyBeforePageLoadHistogram, ("Event.Touch.TouchLatencyBeforePageLoad", 1, 100000000, 50));
-                    eventLatencyBeforePageLoadHistogram.count(latencyInMicros);
+                        DEFINE_STATIC_LOCAL(CustomCountHistogram, eventLatencyBeforePageLoadHistogram, ("Event.Touch.TouchLatencyBeforePageLoad", 1, 100000000, 50));
+                        eventLatencyBeforePageLoadHistogram.count(latencyInMicros);
+                    }
                 }
 
                 // Report the touch disposition, split by whether there is an active fling animation.
-                if (event.type() == PlatformEvent::TouchStart) {
-                    if (event.dispatchedDuringFling()) {
-                        DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsDuringFlingHistogram, ("Event.Touch.TouchDispositionsDuringFling", TouchEventDispatchResultTypeMax));
+                if (event.dispatchedDuringFling()) {
+                    if (event.dispatchType() == PlatformEvent::ListenersForcedNonBlockingPassiveDueToFling) {
+                        DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsDuringFlingHistogram, ("Event.Touch.TouchDispositionsDuringFling2", TouchEventDispatchResultTypeMax));

[dtapuska, 2016/08/10 14:47:42]

if it is forced to be non blocking then it will always be not handled won't it.
because you can't prevent default it?

we might need a uma metric to track how many times preventDefault was called
inside a intervened event; that may be a useful metric. I'm not sure this is
really caturing that.

                         touchDispositionsDuringFlingHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? HandledTouches : UnhandledTouches);
-                    } else {
-                        DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsOutsideFlingHistogram, ("Event.Touch.TouchDispositionsOutsideFling", TouchEventDispatchResultTypeMax));
+                    }
+                } else {
+                    if (event.cancelable()) {
+                        DEFINE_STATIC_LOCAL(EnumerationHistogram, touchDispositionsOutsideFlingHistogram, ("Event.Touch.TouchDispositionsOutsideFling2", TouchEventDispatchResultTypeMax));
                         touchDispositionsOutsideFlingHistogram.count((domDispatchResult != DispatchEventResult::NotCanceled) ? HandledTouches : UnhandledTouches);
                     }
                 }