Introduce use counters for Blink specific editing event usage

Source/core/events/EventTarget.cpp

Index: Source/core/events/EventTarget.cpp
diff --git a/Source/core/events/EventTarget.cpp b/Source/core/events/EventTarget.cpp
index 3f1b07283c7ce7667810b795c23d42d9ec96b560..fa2becc13517105c0a18a8b43e955d7d451b6cdc 100644
--- a/Source/core/events/EventTarget.cpp
+++ b/Source/core/events/EventTarget.cpp
@@ -32,6 +32,8 @@
 #include "config.h"
 #include "core/events/EventTarget.h"
 
+#include "EventTypeNames.h"
+#include "HTMLNames.h"
 #include "RuntimeEnabledFeatures.h"
 #include "bindings/v8/ExceptionState.h"
 #include "core/dom/ExceptionCode.h"
@@ -39,6 +41,7 @@
 #include "core/events/Event.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/frame/DOMWindow.h"
+#include "core/frame/UseCounter.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/Vector.h"
 
@@ -80,12 +83,45 @@ inline DOMWindow* EventTarget::executingWindow()
     return 0;
 }
 
+static void countByObjectType(const EventTarget* eventTarget, UseCounter::Feature featureOnInput, UseCounter::Feature featureOnTextArea, UseCounter::Feature featureOnContentEditable, UseCounter::Feature featureOnNonNode)
+{
+    UseCounter::Feature feature = featureOnNonNode;
+    if (const Node* node = const_cast<EventTarget*>(eventTarget)->toNode()) {
+        if (node->hasTagName(HTMLNames::inputTag))
+            feature = featureOnInput;
+        else if (node->hasTagName(HTMLNames::textareaTag))
+            feature = featureOnTextArea;
+        else
+            feature = featureOnContentEditable;
+    }
+    if (ExecutionContext* context = eventTarget->executionContext())
+        UseCounter::count(context, feature);
+}
+
 bool EventTarget::addEventListener(const AtomicString& eventType, PassRefPtr<EventListener> listener, bool useCapture)
 {
     // FIXME: listener null check should throw TypeError (and be done in
     // generated bindings), but breaks legacy content. http://crbug.com/249598
     if (!listener)
         return false;
+
+    if (eventType == EventTypeNames::textInput) {

[tkent, 2014/06/10 08:19:59]

EventTarget is a generic interface, and I feel adding feature-specific code like
this is not suitable.
Can you move the code to Editor, and call it from here?
Something like...

  if (DOMWInodow* window = executingWindow())
      window->frame()->editor().countEvents(eventType)


Also, you should count EventTarget::fireEventListeners rather than
addEventListeners because we can attach a listener to an ancestor node of the
target node.

[yosin_UTC9, 2014/06/11 00:48:20]

Done.

+        countByObjectType(this, UseCounter::TextInputEventOnInput,
+            UseCounter::TextInputEventOnTextArea,
+            UseCounter::TextInputEventOnContentEditable,
+            UseCounter::TextInputEventOnNotNode);
+    } else if (eventType == EventTypeNames::webkitBeforeTextInserted) {
+        countByObjectType(this, UseCounter::WebkitBeforeTextInsertedOnInput,
+            UseCounter::WebkitBeforeTextInsertedOnTextArea,
+            UseCounter::WebkitBeforeTextInsertedOnContentEditable,
+            UseCounter::WebkitBeforeTextInsertedOnNotNode);
+    } else if (eventType == EventTypeNames::webkitEditableContentChanged) {
+        countByObjectType(this, UseCounter::WebkitEditableContentChangedOnInput,
+            UseCounter::WebkitEditableContentChangedOnTextArea,
+            UseCounter::WebkitEditableContentChangedOnContentEditable,
+            UseCounter::WebkitEditableContentChangedOnNotNode);
+    }
+
     return ensureEventTargetData().eventListenerMap.add(eventType, listener, useCapture);
 }