Add an iframe permissions= attribute for implementing permission delegation

third_party/WebKit/Source/core/html/HTMLIFrameElementSandbox.cpp

 // Copyright 2016 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 "core/html/HTMLIFrameElementSandbox.h"
 
 namespace blink {
 
+namespace {
+
+const char* kSupportedTokens[] = {
+    "allow-forms",
+    "allow-modals",
+    "allow-pointer-lock",
+    "allow-popups",
+    "allow-popups-to-escape-sandbox",
+    "allow-same-origin",
+    "allow-scripts",
+    "allow-top-navigation"
+};
+
+bool IsTokenSupported(const AtomicString& token)
+{
+    for (const char* supportedToken : kSupportedTokens) {
+        if (token == supportedToken)
+            return true;
+    }
+    return false;
+}
+
+} // namespace
+
 HTMLIFrameElementSandbox::HTMLIFrameElementSandbox(DOMTokenListObserver* observer)
     : DOMTokenList(observer)
 {
 }
 
 HTMLIFrameElementSandbox::~HTMLIFrameElementSandbox()
 {
 }
 
-using SandboxSupportedTokens = HashSet<AtomicString>;
-
-static SandboxSupportedTokens& supportedTokens()
-{
-    DEFINE_STATIC_LOCAL(SandboxSupportedTokens, supportedValues, ());
-    if (supportedValues.isEmpty()) {
-        supportedValues.add("allow-forms");
-        supportedValues.add("allow-modals");
-        supportedValues.add("allow-pointer-lock");
-        supportedValues.add("allow-popups");
-        supportedValues.add("allow-popups-to-escape-sandbox");
-        supportedValues.add("allow-same-origin");
-        supportedValues.add("allow-scripts");
-        supportedValues.add("allow-top-navigation");
-    }
-
-    return supportedValues;
-}
-
 bool HTMLIFrameElementSandbox::validateTokenValue(const AtomicString& tokenValue, ExceptionState&) const
 {
-    return supportedTokens().contains(tokenValue);
+    return IsTokenSupported(tokenValue);
 }
 
 } // namespace blink