Extend iframe with a new allowusermedia attribute

getusermedia.html

@@ -2655,6 +2655,17 @@ <h3>MediaDevices Interface Extensions</h3>
               <p>If <var>requestedMediaTypes</var> is the empty set, return a
               promise rejected with a <code>TypeError</code>.</p>
             </li>
+            <li>
+              <p>If the current [[!HTML51]] <a href=
+              "https://www.w3.org/TR/2015/WD-html51-20150506/browsers.html#browsing-context">
+              browsing context</a> is a <a href=
+              "https://www.w3.org/TR/2015/WD-html51-20150506/browsers.html#nested-browsing-context">
+              nested browsing context</a> which is not <a>allowed to use user
+              media</a>, return a promise rejected with a
+              <code><a>DOMException</a></code> object whose
+              <code><a>name</a></code> attribute has the value
+              <code>SecurityError</code>.</p>
+            </li>
             <li>
               <p>Let <var>p</var> be a new promise.</p>
             </li>
@@ -2876,6 +2887,36 @@ <h2>NavigatorUserMediaErrorCallback</h2>
         object or an <code><a>OverconstrainedError</a></code> object.
       </div>
     </section>
+    <section>
+      <h2>User Media in an IFrame</h2>
+      <p>There are some special circumstances when an [[!HTML51]]
+      <code><a href="https://www.w3.org/TR/2015/WD-html51-20150506/semantics.html#the-iframe-element">
+      iframe</a></code> wants to use user media. The iframe needs explicit
+      permission from the embedding page and it needs to identify itself in the
+      security prompt presented to the user. This section, together with the
+      <code><a>getUserMedia()</a></code> algorithm, specifies that
+      behavior.</p>
+      <p>The <code><a>HTMLIFrameElement</a></code> is extended with an <dfn id=
+      "iframe-allowusermedia"><code>allowusermedia</code></dfn> content
+      attribute. <code>allowusermedia</code> is a [[!HTML51]] <code><a href=
+      "https://www.w3.org/TR/2015/WD-html51-20150506/infrastructure.html#boolean-attribute">
+      boolean attribute</a></code>. When specified, it indicates that scripts
+      in the iframe element's browsing context are <dfn>allowed to use user
+      media</dfn> (if it's not blocked for other reasons, e.g. there is another
+      ancestor iframe without this attribute set).</p>
+      <p>The iframe DOM interface is extended as described by the partial
+      interface below.</p>
+      <dl class="idl" title="partial interface HTMLIFrameElement">
+        <dt>attribute boolean allowUserMedia</dt>
+        <dd>
+          <p>The allowUserMedia IDL attribute MUST [[!HTML51]] <code><a href=
+          "https://www.w3.org/TR/2015/WD-html51-20150506/infrastructure.html#reflect">
+          reflect</a></code> the <code><a href=
+          "#iframe-allowusermedia">allowusermedia</a></code> content
+          attribute.</p>
+        </dd>
+      </dl>
+    </section>
     <section>
       <h2>Implementation Suggestions</h2>
       <div class="practice">