Add CreateEventEnabled for make_event_factory to use in IDL file.

This allows an IDL file to specify whether CreateEvent is enabled
without using the blanket RuntimeEnabled definition hack.

This also removes need for strange and error-prone entry override
in EventAliases.in

BUG=332588

Review-Url: https://codereview.chromium.org/2633383005
Cr-Commit-Position: refs/heads/master@{#444662}

third_party/WebKit/Source/bindings/IDLExtendedAttributes.md

@@ -788,6 +788,20 @@ When`[Custom]` is specified on a callback function, the code generator doesn't
 generate bindings for the callback function. The binding layer uses a
 `ScriptValue` instead.
 
+### [CreateEventEnabled] _(i, m, a, c)_
+
+Summary: Like `[RuntimeEnabled]`, it controls at runtime whether bindings are exposed, but only affects createEvent support. See crbug.com/392584#c22.
+
+Usage: `[CreateEventEnabled=FeatureName]`. FeatureName must be included in [RuntimeEnabledFeatures.in](https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in) like RuntimeEnabled.
+
+```webidl
+[
+    CreateEventEnabled=TouchEventFeatureDetection
+] interface TouchEvent : UIEvent { ... };
+```
+
+The feature is enabled at runtime and the createEvent operation will throw exception on the web if disabled. It's worth noting the event constructor (modern way of creating events) still works, so this is used only for very special case legacy compat issues (probably nothing ever other than TouchEvent).
+
 #### [Custom=PropertyQuery|PropertyEnumerator] _(s)_
 
 Summary: `[Custom=PropertyEnumerator]` allows you to write custom bindings for the case where properties of a given interface are enumerated; a custom named enumerator. There is currently only one use, and in that case it is used with `[Custom=PropertyQuery]`, since the query is also custom.

third_party/WebKit/Source/bindings/IDLExtendedAttributes.txt

@@ -42,6 +42,7 @@ Constructor
 # FIXME: remove [ConstructorCallWith=Document], as can instead use
 # [ConstructorCallWith=ExecutionContext] + toDocument(executionContext)
 ConstructorCallWith=ExecutionContext|ScriptState|Document
+CreateEventEnabled=*
 CrossOrigin=|Getter|Setter
 Custom=|Getter|Setter|LegacyCallAsFunction|VisitDOMWrapper|PropertyGetter|PropertyEnumerator|PropertyQuery|CallPrologue|CallEpilogue
 CustomConstructor

third_party/WebKit/Source/build/scripts/make_event_factory.py

@@ -104,6 +104,7 @@ def measure_name(name):
 
 class EventFactoryWriter(in_generator.Writer):
     defaults = {
+        'CreateEventEnabled': None,
         'ImplementedAs': None,
         'RuntimeEnabled': None,
     }
@@ -125,25 +126,14 @@ def __init__(self, in_file_path):
         super(EventFactoryWriter, self).__init__(in_file_path)
         self.namespace = self.in_file.parameters['namespace'].strip('"')
         self.suffix = self.in_file.parameters['suffix'].strip('"')
-        self._validate_entries()
+        # Set CreateEventEnabled if feature is RuntimeEnabled (see crbug.com/332588).
+        for entry in self.in_file.name_dictionaries:
+            if 'RuntimeEnabled' in entry and 'CreateEventEnabled' not in entry:
+                entry['CreateEventEnabled'] = entry['RuntimeEnabled']
         self._outputs = {(self.namespace + self.suffix + "Headers.h"): self.generate_headers_header,
                          (self.namespace + self.suffix + ".cpp"): self.generate_implementation,
                         }
 
-    def _validate_entries(self):
-        # If there is more than one entry with the same script name, only the first one will ever
-        # be hit in practice, and so we'll silently ignore any properties requested for the second
-        # (like RuntimeEnabled - see crbug.com/332588).
-        entries_by_script_name = dict()
-        for entry in self.in_file.name_dictionaries:
-            script_name = name_utilities.script_name(entry)
-            if script_name in entries_by_script_name:
-                self._fatal('Multiple entries with script_name=%(script_name)s: %(name1)s %(name2)s' % {
-                    'script_name': script_name,
-                    'name1': entry['name'],
-                    'name2': entries_by_script_name[script_name]['name']})
-            entries_by_script_name[script_name] = entry
-
     def _fatal(self, message):
         print 'FATAL ERROR: ' + message
         exit(1)

third_party/WebKit/Source/build/scripts/templates/EventFactory.cpp.tmpl

@@ -16,9 +16,9 @@ namespace blink {
 {{namespace}}* {{namespace}}{{suffix}}Factory::create(ExecutionContext* executionContext, const String& type) {
   {% for event in events if event|script_name|create_event_whitelist or event|script_name|create_event_legacy_whitelist %}
   {% if event|script_name|create_event_whitelist %}
-  if (equalIgnoringCase(type, "{{event|script_name}}"){% if event.RuntimeEnabled %} && RuntimeEnabledFeatures::{{event.RuntimeEnabled|lower_first}}(){% endif %}) {
+  if (equalIgnoringCase(type, "{{event|script_name}}"){% if event.CreateEventEnabled %} && RuntimeEnabledFeatures::{{event.CreateEventEnabled|lower_first}}(){% endif %}) {
   {% else %}
-  if (type == "{{event|script_name}}"{% if event.RuntimeEnabled %} && RuntimeEnabledFeatures::{{event.RuntimeEnabled|lower_first}}(){% endif %}) {
+  if (type == "{{event|script_name}}"{% if event.CreateEventEnabled %} && RuntimeEnabledFeatures::{{event.CreateEventEnabled|lower_first}}(){% endif %}) {
   {% endif %}
     {% if not event|script_name|create_event_whitelist %}
     UseCounter::count(executionContext, UseCounter::{{event|script_name|measure_name}});

third_party/WebKit/Source/core/events/EventAliases.in

@@ -8,5 +8,3 @@ MutationEvents ImplementedAs=MutationEvent
 SVGEvents ImplementedAs=Event
 UIEvents ImplementedAs=UIEvent
 WebKitTransitionEvent ImplementedAs=TransitionEvent
-
-core/events/TouchEvent RuntimeEnabled=touchEventFeatureDetectionEnabled

third_party/WebKit/Source/core/events/TouchEvent.idl

@@ -27,6 +27,7 @@
 
 [
     Constructor(DOMString type, optional TouchEventInit eventInitDict),
+    CreateEventEnabled=TouchEventFeatureDetection,
 ] interface TouchEvent : UIEvent {
     readonly attribute TouchList touches;
     readonly attribute TouchList targetTouches;