[COOP] access reporting: fix flakes reporting.html (#25834)

---

The WPT testharness.js is defining:
```
WindowTestEnvironment.prototype._forEach_windows = function(callback) {
// Iterate over the windows [self ... top, opener]. The callback is
// passed two objects, the first one is the window object itself, the
// second one is a boolean indicating whether or not it's on the same
// origin as the (...)
```

This causes some postMessage to be sent cross-window. They are reported
and causes failures. For instance in reporting-observer.html test.

This patch removes testharness.js from executor.html
This fixed the issue for reporting-observer.html

More generally, we shouldn't check access in between two windows, when
one of them is using testharness.js

---

Second discovery:
The official web-platform-test runner sometimes drop POST requests
when many are requested in parallel. Using a lock fixes the issue.

---

Bug: 1090273
Change-Id: I261b9bfece935e3613c250a3a9402a1c8a6ff14e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2436742
Commit-Queue: Arthur Sonzogni <[email protected]>
Reviewed-by: Pâris Meuleman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#855712}

Co-authored-by: arthursonzogni <[email protected]>

html/cross-origin-opener-policy/reporting/resources/dispatcher.js

@@ -10,22 +10,27 @@ const dispatcher_path =
     '/html/cross-origin-opener-policy/reporting/resources/dispatcher.py';
 const dispatcher_url = new URL(dispatcher_path, location.href).href;
 
-const send = function(uuid, message) {
-  fetch(dispatcher_url + `?uuid=${uuid}`, {
-    method: 'POST',
-    body: message
+const send = async function(uuid, message) {
+  // The official web-platform-test runner sometimes drop POST requests when
+  // many are requested in parallel. Using a lock fixes the issue.
+  await navigator.locks.request("dispatcher_send", async lock => {
+    await fetch(dispatcher_url + `?uuid=${uuid}`, {
+      method: 'POST',
+      body: message
+    });
   });
 }
 
 const receive = async function(uuid, maybe_timeout) {
   const timeout = maybe_timeout || Infinity;
-  const retry_delay = 100;
-  for(let i = 0; i * retry_delay < timeout; ++i) {
+  let start = performance.now();
+  while(performance.now() - start < timeout) {
     let response = await fetch(dispatcher_url + `?uuid=${uuid}`);
     let data = await response.text();
     if (data != 'not ready')
       return data;
-    await new Promise(r => step_timeout(r, retry_delay));
+    // Save resources & spread the load:
+    await new Promise(r => setTimeout(r, 100*Math.random()));
   }
   return "timeout";
 }

html/cross-origin-opener-policy/reporting/resources/executor.html

@@ -1,4 +1,3 @@
-<script src=/resources/testharness.js></script>
 <script src="./dispatcher.js"></script>
 <script src="./try-access.js"></script>
 <script>

lint.ignore

@@ -309,6 +309,7 @@ SET TIMEOUT: feature-policy/experimental-features/resources/focus-without-user-a
 SET TIMEOUT: permissions-policy/experimental-features/resources/focus-without-user-activation-iframe-tentative.html
 SET TIMEOUT: html/browsers/windows/auxiliary-browsing-contexts/resources/close-opener.html
 SET TIMEOUT: html/cross-origin-embedder-policy/resources/reporting-worker.js
+SET TIMEOUT: html/cross-origin-opener-policy/reporting/resources/dispatcher.js
 SET TIMEOUT: html/dom/documents/dom-tree-accessors/Document.currentScript.html
 SET TIMEOUT: html/webappapis/timers/*
 SET TIMEOUT: orientation-event/resources/orientation-event-helpers.js