[bindings] Implement an ExperimentEnabled IDL extended attribute.

third_party/WebKit/Source/core/experiments/Experiments.cpp

 // 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 "config.h"
 #include "core/experiments/Experiments.h"
 
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/html/HTMLHeadElement.h"
@@ skipping 39 matching lines @@
     } else {
         errorMessage = getDisabledMessage(apiName);
     }
     return false;
 }
 
 } // namespace
 
 bool Experiments::isApiEnabled(ExecutionContext* executionContext, const String& apiName, String& errorMessage)
 {
+    return isApiEnabledInternal(executionContext, apiName, errorMessage);
+}
+
+bool Experiments::isApiEnabled(ExecutionContext* executionContext, const String& apiName)
+{
+    String errorMessage;
+    return isApiEnabledInternal(executionContext, apiName, errorMessage);
+}
+
+bool Experiments::isApiEnabledInternal(ExecutionContext* executionContext, const String& apiName, String& errorMessage)
+{
     if (!RuntimeEnabledFeatures::experimentalFrameworkEnabled()) {
         errorMessage = "Experimental Framework is not enabled.";
         return false;
     }
 
     if (!executionContext) {
         ASSERT_NOT_REACHED();
         return false;
     }
 
     // Experiments are only enabled for secure origins
     if (!executionContext->isSecureContext(errorMessage)) {
         return false;
     }
 
     return hasValidAPIKey(executionContext, apiName, errorMessage);
 }
 
 DOMException* Experiments::createApiDisabledException(const String& apiName)
 {
     return DOMException::create(NotSupportedError, getDisabledMessage(apiName));
 }
 
 } // namespace blink