Add navigationId to PerformanceEntry

index.html

@@ -70,6 +70,9 @@
       </li>
       <li>Exposes {{PerformanceEntry}} in Web Workers [[WORKERS]];
       </li>
+      <li>Formalizes support for multiple navigation events over a document's
+      lifetime.
+      </li>
       <li>Adds support for {{PerformanceObserver}}.
       </li>
     </ul>
@@ -246,6 +249,7 @@ <h2><dfn>Performance Timeline</dfn></h2>
           <li>An integer <dfn>dropped entries count</dfn> that is initially 0.</li>
         </ul>
       </li>
+      <li>An integer <dfn>current navigation id</dfn> that is initially 0.</li>
     </ul>
     <p>In order to get the <dfn>relevant performance entry tuple</dfn>, given
     <var>entryType</var> and <var>globalObject</var> as input, run the
@@ -258,6 +262,17 @@ <h2><dfn>Performance Timeline</dfn></h2>
         map</var>, given <var>entryType</var> as the <a>key</a>.
       </li>
     </ol>
+    <p>The <a
+    href="https://html.spec.whatwg.org/#session-history-document-visibility-change-steps">session
+    history document visibility change steps</a> defined by this specification are:</p>
+    <ol>
+      <li>Increment <var>newDocument</var>'s [=relevant global object=]'s <a>current navigation
+      id</a>.</li>
+    </ol>
+    <p class="note">These steps will be called from [[HTML]]'s <a
+    href="https://html.spec.whatwg.org/#traverse-the-history">traverse the history</a>
+    algorithm whenever a document is restored from the bfcache, immediately before the
+    [=Window/pageshow=] event is fired.</p>
     <section data-dfn-for="Performance" data-link-for="Performance">
       <h2>Extensions to the {{Performance}} interface</h2>
       <p>This extends the {{Performance}} interface from [[HR-TIME-3]] and
@@ -308,6 +323,7 @@ <h2>The <dfn>PerformanceEntry</dfn> interface</h2>
         readonly    attribute DOMString           entryType;
         readonly    attribute DOMHighResTimeStamp startTime;
         readonly    attribute DOMHighResTimeStamp duration;
+        readonly    attribute unsigned long       navigationId;
         [Default] object toJSON();
       };</pre>
     <dl>
@@ -344,6 +360,12 @@ <h2>The <dfn>PerformanceEntry</dfn> interface</h2>
         duration concept doesn't apply, a performance metric may choose to
         return a `duration` of <code>0</code>.
       </dd>
+      <dt><dfn>navigationId</dfn></dt>
+      <dd>
+        This attribute MUST return the value of the global object's <a>current
+        navigation id</a> at the time that this <a>PerformanceEntry</a> was
+        queued.
+      </dd>
     </dl>
     <p>When <dfn>toJSON</dfn> is called, run [[WebIDL]]'s <a>default toJSON
     steps</a>.</p>
@@ -672,6 +694,8 @@ <h2>Queue a <code>PerformanceEntry</code></h2>
         <li>Let <var>relevantGlobal</var> be <var>newEntry</var>'s <a>relevant
         global object</a>.
         </li>
+        <li>Set <var>newEntry</var>'s <a data-lt="PerformanceEntry.navigationId">navigationId</a>
+        to <var>relevantGlobal</var>'s <a>current navigation id</a>.</li>
         <li>For each <a>registered performance observer</a> <var>regObs</var> in
         <var>relevantGlobal</var>'s <a>list of registered performance observer objects</a>:
           <ol>