[bindings] Implement an ExperimentEnabled IDL extended attribute.

third_party/WebKit/Source/bindings/scripts/v8_utilities.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 362 matching lines @@
         return lambda suffix: extended_attributes['MeasureAs']
     if 'Measure' in extended_attributes:
         includes.add('core/frame/UseCounter.h')
         measure_as_name = capitalize(definition_or_member.name)
         if interface is not None:
             measure_as_name = '%s_%s' % (capitalize(interface.name), measure_as_name)
         return lambda suffix: 'V8%s_%s' % (measure_as_name, suffix)
     return None
 
 
+def runtime_feature_name(definition_or_member):
+    extended_attributes = definition_or_member.extended_attributes
+    if 'RuntimeEnabled' not in extended_attributes:
+        return None
+    return extended_attributes['RuntimeEnabled']
+
+
+def is_api_experiment_enabled(interface):

[haraken, 2015/12/30 00:25:32]

interface => definition_or_member ?

[Daniel Nishi, 2015/12/30 22:05:50]

Done.

+    return 'APIExperimentEnabled' in interface.extended_attributes
+
+
+def api_experiment_name(interface):
+    return interface.extended_attributes['APIExperimentEnabled'] if is_api_experiment_enabled(interface) else None
+
+
+def api_experiment_enabled_function(definition_or_member):
+    experiment_name = api_experiment_name(definition_or_member)
+    feature_name = runtime_feature_name(definition_or_member)
+    if not feature_name or not experiment_name:

[haraken, 2015/12/30 00:25:32]

Why do we need to check 'not feature_name'? Aren't we just ignoring the
[RuntimeEnabled] if [APIExperimentEnabled] is specified at the same time?

[Daniel Nishi, 2015/12/30 22:05:50]

https://codereview.chromium.org/1538663003/ uses the FeatureName to generate the
ExperimentalFeatures::%sEnabled function. Without a feature name, we don't know
what to use.

+        return
+    return 'ExperimentalFeatures::%sEnabled' % uncapitalize(feature_name)
+
+
 # [RuntimeEnabled]
 def runtime_enabled_function_name(definition_or_member):
     """Returns the name of the RuntimeEnabledFeatures function.
 
     The returned function checks if a method/attribute is enabled.
     Given extended attribute RuntimeEnabled=FeatureName, return:
         RuntimeEnabledFeatures::{featureName}Enabled
     """
-    extended_attributes = definition_or_member.extended_attributes
-    if 'RuntimeEnabled' not in extended_attributes:
-        return None
-    feature_name = extended_attributes['RuntimeEnabled']
+    feature_name = runtime_feature_name(definition_or_member)
+
+    # If an experiment is on the method/attribute, it overrides the runtime

[haraken, 2015/12/30 00:25:32]

experiment => API experiment

("experiment" sounds too generic.)

[Daniel Nishi, 2015/12/30 22:05:50]

Done.

+    # enabled status. For now, we are unconditionally installing experimental
+    # attributes/methods, so we are acting as though the runtime enabled
+    # function doesn't exist. (It is checked in the generated
+    # ExperimentalFeatures function, instead)
+    experiment_name = api_experiment_name(definition_or_member)
+    if not feature_name or experiment_name:
+        return
     return 'RuntimeEnabledFeatures::%sEnabled' % uncapitalize(feature_name)
 
 
 # [Unforgeable]
 def is_unforgeable(interface, member):
     return (('Unforgeable' in interface.extended_attributes or
              'Unforgeable' in member.extended_attributes) and
             not member.is_static)
 
 
@@ skipping 173 matching lines @@
     except StopIteration:
         return None
 
 
 IdlInterface.indexed_property_getter = property(indexed_property_getter)
 IdlInterface.indexed_property_setter = property(indexed_property_setter)
 IdlInterface.indexed_property_deleter = property(indexed_property_deleter)
 IdlInterface.named_property_getter = property(named_property_getter)
 IdlInterface.named_property_setter = property(named_property_setter)
 IdlInterface.named_property_deleter = property(named_property_deleter)