Make registration.update() no longer force bypassing the HTTP cache (1/2)

LayoutTests/http/tests/serviceworker/ServiceWorkerGlobalScope/resources/update-worker.php

Index: LayoutTests/http/tests/serviceworker/ServiceWorkerGlobalScope/resources/update-worker.php
diff --git a/LayoutTests/http/tests/serviceworker/ServiceWorkerGlobalScope/resources/update-worker.php b/LayoutTests/http/tests/serviceworker/ServiceWorkerGlobalScope/resources/update-worker.php
index 2486820c26c5f6483270a2d15f6527ec3ee11662..b64198aa978aa0bd893fbb55982732fe0eaee680 100644
--- a/LayoutTests/http/tests/serviceworker/ServiceWorkerGlobalScope/resources/update-worker.php
+++ b/LayoutTests/http/tests/serviceworker/ServiceWorkerGlobalScope/resources/update-worker.php
@@ -1,8 +1,21 @@
 <?php
-// Force the browser to cache this script. update() should always bypass this
-// cache and fetch a new version.
-header('Cache-Control: max-age=86400');
-
+if(!isset($_COOKIE['mode']))
+  $mode = 'no-cache'; // Set mode to 'no-cache' for initial register().
+else
+  $mode = $_COOKIE['mode'];
+
+if ($mode == 'no-cache') {
+  // Set max-age to 0 so the next update will go to the network.
+  // Set cookie value to 'cache' so the next fetch will work in 'cache' mode.
+  header('Cache-Control: max-age=0');
+  setcookie('mode', 'cache');
+} else if ($mode == 'cache') {
+  // Set max-age to non-zero value so the next update will be served from cache.
+  // Unset cookie value.
+  header('Cache-Control: max-age=3600');
+  unset($_COOKIE['mode']);
+  setcookie('mode', '', time() - 3600);
+}
 // Return a different script for each access.
 header('Content-Type:application/javascript');
 echo '// ' . microtime();
@@ -24,11 +37,26 @@ self.addEventListener('activate', function(e) {
 self.addEventListener('fetch', function(e) {
     events_seen.push('fetch');
     e.respondWith(new Response(events_seen));
+    events_seen = []; // Init events_seen for the next update.
   });
 
 self.addEventListener('message', function(e) {
     events_seen.push('message');
-    self.registration.update();
+    self.registration.update()
+      .then(function() {
+          if (self.registration.installing) // A new version found.
+            events_seen.push('new-version');
+          else                              // The same version served.
+            events_seen.push('cached-version');
+
+          self.clients.matchAll().then(function(clients) {
+              clients.forEach(function(c) {
+                  if (c.url == e.data) {
+                    c.postMessage('update resolved');
+                  }
+                });
+            });
+        });
   });
 
 // update() during the script evaluation should be ignored.