Prerender: Test that clients in prerendering state are exposed via Clients#matchAll()

By adding a new browser test, this CL clarifies the current behavior that clients in the prerendering state are exposed via Clients#matchAll() on service workers. This behavior can be changed based on future discussions. Change-Id: I6be9d2e3db91a5b411a5debbe4098a83597f4f86 Bug: 1166470 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2626861Reviewed-by: Matt Falkenhagen <falken@chromium.org> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org> Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org> Cr-Commit-Position: refs/heads/master@{#844487}

Prerender: Test that clients in prerendering state are exposed via Clients#matchAll()
By adding a new browser test, this CL clarifies the current behavior that clients in the prerendering state are exposed via Clients#matchAll() on service workers. This behavior can be changed based on future discussions. Change-Id: I6be9d2e3db91a5b411a5debbe4098a83597f4f86 Bug: 1166470 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2626861Reviewed-by: Matt Falkenhagen <falken@chromium.org> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org> Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org> Cr-Commit-Position: refs/heads/master@{#844487}
69b81d79 · Hiroki Nakagawa · Chromium LUCI CQ · e1e04cce · 69b81d79 · 69b81d79
Commit 69b81d79 authored Jan 18, 2021 by Hiroki Nakagawa Committed by Chromium LUCI CQ Jan 18, 2021
3 changed files
--- a/content/browser/prerender/prerender_browsertest.cc
+++ b/content/browser/prerender/prerender_browsertest.cc
@@ -470,5 +470,33 @@ IN_PROC_BROWSER_TEST_P(PrerenderBrowserTest, FeatureRestriction_WindowOpen) {
  EXPECT_EQ(registry.FindHostByUrlForTesting(kPrerenderingUrl), prerender_host);
 }
+// Tests that Clients#matchAll() on ServiceWorkerGlobalScope exposes clients in
+// the prerendering state.
+// TODO(https://crbug.com/1166470): This can be a tentative behavior. We may
+// stop exposing the clients.
+IN_PROC_BROWSER_TEST_P(PrerenderBrowserTest,
+                       FeatureRestriction_ClientsMatchAll) {
+  // Navigate to an initial page.
+  const GURL kInitialUrl = GetUrl("/prerender/clients_matchall.html");
+  ASSERT_TRUE(NavigateToURL(shell(), kInitialUrl));
+  // Start a prerender.
+  const GURL kPrerenderingUrl = GetUrl("/empty.html");
+  AddPrerender(kPrerenderingUrl);
+  PrerenderHostRegistry& registry = GetPrerenderHostRegistry();
+  PrerenderHost* prerender_host =
+      registry.FindHostByUrlForTesting(kPrerenderingUrl);
+  ASSERT_TRUE(prerender_host);
+  // Make sure the prerendering page is exposed via Clients#matchAll().
+  EvalJsResult results =
+      EvalJs(shell()->web_contents(), "get_exposed_client_urls()");
+  std::vector<std::string> client_urls;
+  for (auto& result : results.ExtractList())
+    client_urls.push_back(result.GetString());
+  EXPECT_TRUE(base::Contains(client_urls, kInitialUrl));
+  EXPECT_TRUE(base::Contains(client_urls, kPrerenderingUrl));
+}
 }  // namespace
 }  // namespace content
--- a/content/test/data/prerender/clients_matchall.html
+++ b/content/test/data/prerender/clients_matchall.html
+<!DOCTYPE html>
+<html>
+<head></head>
+<body></body>
+<script>
+// Adds <link rel=prerender> for the URL.
+function add_prerender(url) {
+  const link = document.createElement('link');
+  link.rel = 'prerender';
+  link.href = url;
+  document.head.appendChild(link);
+}
+async function unregister_service_worker(scope) {
+  const registration = await navigator.serviceWorker.getRegistration(scope);
+  if (!registration)
+    return;
+  return registration.unregister();
+}
+// Returns client urls exposed by Clients#matchAll().
+async function get_exposed_client_urls() {
+  // Start a service worker.
+  const worker_url = 'clients_matchall_service_worker.js';
+  const scope = 'controlled/';
+  await unregister_service_worker(scope);
+  const registration =
+      await navigator.serviceWorker.register(worker_url, { scope: scope });
+  // Ask the service worker to run Clients#matchAll().
+  const message = await new Promise(resolve => {
+    registration.installing.postMessage('matchall');
+    navigator.serviceWorker.onmessage = resolve;
+  });
+  // `data` contains client URLs.
+  return message.data;
+}
+</script>
+</html>
--- a/content/test/data/prerender/clients_matchall_service_worker.js
+++ b/content/test/data/prerender/clients_matchall_service_worker.js
+// Copyright 2021 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.
+onmessage = e => {
+  // Collect all client URLs in this origin.
+  const options = { includeUncontrolled: true, type: 'all' };
+  const promise = self.clients.matchAll(options)
+      .then(clients => {
+        const client_urls = [];
+        clients.forEach(client => client_urls.push(client.url));
+        e.source.postMessage(client_urls);
+      });
+  e.waitUntil(promise);
+};