[prerender] defer SharedStorage worklet creation on prerendering pages

Clqsin45 · chromium-wpt-export-bot · commit bc5b242506be · 2025-03-18T20:51:23.000-07:00
This CL is a follow-up for I7b79bdfc021842f9a803892a1a294e20ffdf8a01, which defers the write operations. Before this CL, prerendering pages will be discarded if JS attempts to create a worklet for SharedStorage. After this CL, the creation will be deferred until page activation. Bug: 390136190 Change-Id: I898a63403728eb8fd716ddc6ab029cabeee48127 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6360936 Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org> Commit-Queue: Lingqi Chi <lingqi@chromium.org> Reviewed-by: Yao Xiao <yaoxia@chromium.org> Cr-Commit-Position: refs/heads/main@{#1434598}
diff --git a/speculation-rules/prerender/resources/shared-storage-worklet.js b/speculation-rules/prerender/resources/shared-storage-worklet.js
@@ -0,0 +1,5 @@
+class ReadOperation {
+  async run() {
+    return await this.sharedStorage.get("prerender");
+  }
+}
diff --git a/speculation-rules/prerender/resources/shared-storage.https.html b/speculation-rules/prerender/resources/shared-storage.https.html
@@ -19,9 +19,20 @@
   loadInitiatorPage();
 } else {
   const prerenderEventCollector = new PrerenderEventCollector();
-  prerenderEventCollector.start(
-    window.sharedStorage.set('prerender', 'yes'), 'window.sharedStorage.set');
+
+  if (params.get('type') === 'worklet') {
+    async function register() {
+      return window.sharedStorage.worklet.addModule(
+        "shared-storage-worklet.js");
+    }
+    prerenderEventCollector.start(
+      register(), 'window.sharedStorage.worklet.addModule');
+  } else {
+    prerenderEventCollector.start(
+      window.sharedStorage.set('prerender', 'yes'),
+      'window.sharedStorage.set');
   }
+}
 
 </script>
 
diff --git a/speculation-rules/prerender/restrictions_shared_storage_worklet.https.html b/speculation-rules/prerender/restrictions_shared_storage_worklet.https.html
@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<title>Worklet operations to Shared Storage API is deferred</title>
+<meta name="timeout" content="long">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/utils.js"></script>
+<script src="../resources/utils.js"></script>
+<script src="resources/utils.js"></script>
+
+<body>
+<script>
+setup(() => assertSpeculationRulesIsSupported());
+promise_test(async t => {
+    const uid = token();
+    const bc = new PrerenderChannel('test-channel', uid);
+
+    const gotMessage = new Promise(resolve => {
+      bc.addEventListener('message', e => {
+        resolve(e.data);
+      }, {
+        once: true
+      });
+    });
+
+    const url =
+      `resources/shared-storage.https.html?uid=${uid}&type=worklet`;
+    window.open(url, '_blank', 'noopener');
+
+    const result = await gotMessage;
+    const expected = [
+      {
+        event: 'started waiting window.sharedStorage.worklet.addModule',
+        prerendering: true
+      },
+      {
+        event: 'prerendering change',
+        prerendering: false
+      },
+      {
+        event: 'finished waiting window.sharedStorage.worklet.addModule',
+        prerendering: false
+      }
+    ];
+    assert_equals(result.length, expected.length);
+    for (let i = 0; i < result.length; i++) {
+      assert_equals(result[i].event, expected[i].event,
+        `event[${i}]`);
+      assert_equals(result[i].prerendering, expected[i].prerendering,
+        `prerendering[${i}]`);
+    }
+    bc.close();
+
+    // Send a close signal to PrerenderEventCollector on the prerendered page.
+    new PrerenderChannel('close', uid).postMessage('');
+  },
+  `add module for the Shared Storage API should be deferred until the
+    prerendered page is activated`);
+</script>
