Revert "UMA metrics for fractions of wheel and touch scrolls blocked on the main thread."

ui/events/blink/input_handler_proxy.cc

Index: ui/events/blink/input_handler_proxy.cc
diff --git a/ui/events/blink/input_handler_proxy.cc b/ui/events/blink/input_handler_proxy.cc
index aa34e84a50f09b61bea59cb40b144119c952b580..50944669c242de0f1bd343f9a3fa22ae12a076d0 100644
--- a/ui/events/blink/input_handler_proxy.cc
+++ b/ui/events/blink/input_handler_proxy.cc
@@ -233,13 +233,6 @@ cc::InputHandler::ScrollInputType GestureScrollInputType(
              : cc::InputHandler::TOUCHSCREEN;
 }
 
-enum ScrollingThreadStatus {
-  SCROLLING_ON_COMPOSITOR,
-  SCROLLING_ON_COMPOSITOR_BLOCKED_ON_MAIN,
-  SCROLLING_ON_MAIN,
-  LAST_SCROLLING_THREAD_STATUS_VALUE = SCROLLING_ON_MAIN,
-};
-
 }  // namespace
 
 namespace ui {
@@ -264,7 +257,6 @@ InputHandlerProxy::InputHandlerProxy(cc::InputHandler* input_handler,
       uma_latency_reporting_enabled_(base::TimeTicks::IsHighResolution()),
       touchpad_and_wheel_scroll_latching_enabled_(false),
       touch_start_result_(kEventDispositionUndefined),
-      mouse_wheel_result_(kEventDispositionUndefined),
       current_overscroll_params_(nullptr),
       has_ongoing_compositor_scroll_pinch_(false),
       tick_clock_(base::MakeUnique<base::DefaultTickClock>()) {
@@ -594,54 +586,6 @@ void InputHandlerProxy::RecordMainThreadScrollingReasons(
   }
 }
 
-void InputHandlerProxy::RecordScrollingThreadStatus(
-    blink::WebGestureDevice device,
-    uint32_t reasons) {
-  DCHECK(device == blink::WebGestureDeviceTouchpad ||
-         device == blink::WebGestureDeviceTouchscreen);
-
-  if (device != blink::WebGestureDeviceTouchpad &&
-      device != blink::WebGestureDeviceTouchscreen) {
-    return;
-  }
-
-  ScrollingThreadStatus scrolling_thread_status = SCROLLING_ON_MAIN;
-  if (reasons == cc::MainThreadScrollingReason::kNotScrollingOnMain) {
-    int32_t event_disposition_result =
-        (device == blink::WebGestureDeviceTouchpad ? mouse_wheel_result_
-                                                   : touch_start_result_);
-    switch (event_disposition_result) {
-      case kEventDispositionUndefined:
-      case DID_NOT_HANDLE_NON_BLOCKING_DUE_TO_FLING:
-      case DID_HANDLE_NON_BLOCKING:
-      case DROP_EVENT:
-        scrolling_thread_status = SCROLLING_ON_COMPOSITOR;
-        break;
-      case DID_NOT_HANDLE:
-        scrolling_thread_status = SCROLLING_ON_COMPOSITOR_BLOCKED_ON_MAIN;
-        break;
-      default:
-        NOTREACHED();
-        scrolling_thread_status = SCROLLING_ON_COMPOSITOR;
-    }
-  }
-
-  // UMA_HISTOGRAM_ENUMERATION requires that the enum_max must be strictly
-  // greater than the sample value.
-  const uint32_t kScrolingThreadStatusEnumMax =
-      ScrollingThreadStatus::LAST_SCROLLING_THREAD_STATUS_VALUE + 1;
-
-  if (device == blink::WebGestureDeviceTouchscreen) {
-    UMA_HISTOGRAM_ENUMERATION("Renderer4.GestureScrollingThreadStatus",
-                              scrolling_thread_status,
-                              kScrolingThreadStatusEnumMax);
-  } else {
-    UMA_HISTOGRAM_ENUMERATION("Renderer4.WheelScrollingThreadStatus",
-                              scrolling_thread_status,
-                              kScrolingThreadStatusEnumMax);
-  }
-}
-
 bool InputHandlerProxy::ShouldAnimate(bool has_precise_scroll_deltas) const {
 #if defined(OS_MACOSX)
   // Mac does not smooth scroll wheel events (crbug.com/574283).
@@ -658,28 +602,21 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleMouseWheel(
   if (!wheel_event.hasPreciseScrollingDeltas && fling_curve_)
     CancelCurrentFling();
 
-  InputHandlerProxy::EventDisposition result = DROP_EVENT;
   cc::EventListenerProperties properties =
       input_handler_->GetEventListenerProperties(
           cc::EventListenerClass::kMouseWheel);
   switch (properties) {
     case cc::EventListenerProperties::kPassive:
-      result = DID_HANDLE_NON_BLOCKING;
-      break;
+      return DID_HANDLE_NON_BLOCKING;
     case cc::EventListenerProperties::kBlockingAndPassive:
     case cc::EventListenerProperties::kBlocking:
-      result = DID_NOT_HANDLE;
-      break;
+      return DID_NOT_HANDLE;
     case cc::EventListenerProperties::kNone:
-      result = DROP_EVENT;
-      break;
+      return DROP_EVENT;
     default:
       NOTREACHED();
-      result = DROP_EVENT;
+      return DROP_EVENT;
   }
-
-  mouse_wheel_result_ = result;
-  return result;
 }
 
 InputHandlerProxy::EventDisposition InputHandlerProxy::FlingScrollByMouseWheel(
@@ -734,13 +671,6 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::FlingScrollByMouseWheel(
         blink::WebGestureDeviceTouchpad,
         scroll_status.main_thread_scrolling_reasons);
 
-    mouse_wheel_result_ =
-        (listener_properties == cc::EventListenerProperties::kPassive)
-            ? DID_HANDLE_NON_BLOCKING
-            : DROP_EVENT;
-    RecordScrollingThreadStatus(blink::WebGestureDeviceTouchpad,
-                                scroll_status.main_thread_scrolling_reasons);
-
     switch (scroll_status.thread) {
       case cc::InputHandler::SCROLL_ON_IMPL_THREAD: {
         TRACE_EVENT_INSTANT2("input",
@@ -822,8 +752,6 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollBegin(
 
   RecordMainThreadScrollingReasons(gesture_event.sourceDevice,
                                    scroll_status.main_thread_scrolling_reasons);
-  RecordScrollingThreadStatus(gesture_event.sourceDevice,
-                              scroll_status.main_thread_scrolling_reasons);
 
   InputHandlerProxy::EventDisposition result = DID_NOT_HANDLE;
   switch (scroll_status.thread) {