Rename EventUtil namepsace to event_util.

https://google.github.io/styleguide/cppguide.html#Namespace_Names
> Namespace names are all lower-case.

This CL has no behavior changes.

Bug: 889726
Change-Id: Ie72fbbaa5ffae8a15fb07356d0e190fd3d140e5c
Reviewed-on: https://chromium-review.googlesource.com/c/1288111Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Zhuoyu Qian <zhuoyu.qian@samsung.com>
Cr-Commit-Position: refs/heads/master@{#600703}

third_party/blink/renderer/core/dom/events/event_target.cc

@@ -419,13 +419,13 @@ void EventTarget::AddedEventListener(
         UseCounter::Count(*document, WebFeature::kAuxclickAddListenerCount);
       else if (event_type == EventTypeNames::appinstalled)
         UseCounter::Count(*document, WebFeature::kAppInstalledEventAddListener);
-      else if (EventUtil::IsPointerEventType(event_type))
+      else if (event_util::IsPointerEventType(event_type))
         UseCounter::Count(*document, WebFeature::kPointerEventAddListenerCount);
       else if (event_type == EventTypeNames::slotchange)
         UseCounter::Count(*document, WebFeature::kSlotChangeEventAddListener);
     }
   }
-  if (EventUtil::IsDOMMutationEventType(event_type)) {
+  if (event_util::IsDOMMutationEventType(event_type)) {
     if (ExecutionContext* context = GetExecutionContext()) {
       String message_text = String::Format(
           "Added synchronous DOM mutation listener to a '%s' event. "

third_party/blink/renderer/core/events/event_util.cc

@@ -8,7 +8,7 @@
 
 namespace blink {
 
-namespace EventUtil {
+namespace event_util {
 
 bool IsPointerEventType(const AtomicString& event_type) {
   return event_type == EventTypeNames::gotpointercapture ||
@@ -32,6 +32,6 @@ bool IsDOMMutationEventType(const AtomicString& event_type) {
          event_type == EventTypeNames::DOMSubtreeModified;
 }
 
-}  // namespace eventUtil
+}  // namespace event_util
 
 }  // namespace blink

third_party/blink/renderer/core/events/event_util.h

@@ -9,13 +9,13 @@
 
 namespace blink {
 
-namespace EventUtil {
+namespace event_util {
 
 bool IsPointerEventType(const AtomicString& event_type);
 
 bool IsDOMMutationEventType(const AtomicString& event_type);
 
-}  // namespace eventUtil
+}  // namespace event_util
 
 }  // namespace blink
 

third_party/blink/renderer/core/frame/event_handler_registry.cc

@@ -74,7 +74,7 @@ bool EventHandlerRegistry::EventTypeToClass(
     // process pointerrawmove events and hit-test them when
     // there is no listener on the page.
     *result = kPointerRawMoveEvent;
-  } else if (EventUtil::IsPointerEventType(event_type)) {
+  } else if (event_util::IsPointerEventType(event_type)) {
     // The pointer events never block scrolling and the compositor
     // only needs to know about the touch listeners.
     *result = kPointerEvent;

third_party/blink/tools/blinkpy/presubmit/audit_non_blink_usage.py

@@ -219,6 +219,7 @@ _CONFIG = [
             'cssvalue::.+',
             'encoding::.+',
             'event_handling_util::.+',
+            'event_util::.+',
             'scheduler::.+',
             'touch_action_util::.+',
             'xpath::.+',