Articulate the cancel behavior in WebMouseWheelEvent.

content/renderer/input/render_widget_input_handler.cc

 // Copyright 2015 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 "content/renderer/input/render_widget_input_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
@@ skipping 310 matching lines @@
   // TODO(dtapuska): Use the input_event.timeStampSeconds as the start
   // ideally this should be when the event was sent by the compositor to the
   // renderer. crbug.com/565348
   if (input_event.type == WebInputEvent::TouchStart ||
       input_event.type == WebInputEvent::TouchMove ||
       input_event.type == WebInputEvent::TouchEnd) {
     LogPassiveEventListenersUma(
         processed, static_cast<const WebTouchEvent&>(input_event).dispatchType,
         input_event.timeStampSeconds, latency_info);
   } else if (input_event.type == WebInputEvent::MouseWheel) {
-    bool non_blocking =
-        dispatch_type ==
-            InputEventDispatchType::DISPATCH_TYPE_NON_BLOCKING_NOTIFY_MAIN ||
-        dispatch_type == InputEventDispatchType::DISPATCH_TYPE_NON_BLOCKING;
-    LogPassiveEventListenersUma(processed,
-                                non_blocking ? WebInputEvent::EventNonBlocking
-                                             : WebInputEvent::Blocking,
-                                input_event.timeStampSeconds, latency_info);
+    LogPassiveEventListenersUma(
+        processed,
+        static_cast<const WebMouseWheelEvent&>(input_event).dispatchType,
+        input_event.timeStampSeconds, latency_info);
   }
 
   // If this RawKeyDown event corresponds to a browser keyboard shortcut and
   // it's not processed by webkit, then we need to suppress the upcoming Char
   // events.
   bool is_keyboard_shortcut =
       input_event.type == WebInputEvent::RawKeyDown &&
       static_cast<const WebKeyboardEvent&>(input_event).isBrowserShortcut;
   if (processed == WebInputEventResult::NotHandled && is_keyboard_shortcut)
     suppress_next_char_events_ = true;
@@ skipping 197 matching lines @@
   if (pending_input_event_ack_) {
     TRACE_EVENT_ASYNC_END0("input",
                            "RenderWidgetInputHandler::ThrottledInputEventAck",
                            pending_input_event_ack_.get());
     delegate_->OnInputEventAck(std::move(pending_input_event_ack_));
   }
   total_input_handling_time_this_frame_ = base::TimeDelta();
 }
 
 }  // namespace content