ServiceWorker: Enable UseCounter for ServiceWorkerGlobalScope

third_party/WebKit/LayoutTests/http/tests/serviceworker/chromium/resources/usecounter-worker.js

+// This should be accessed only in the install event or the message event. When
+// this is false, it implies that this service worker is restarted after the
+// install event.
+let run_install_event = false;

[falken, 2017/02/08 05:01:54]

nit: maybe did_install or did_run_install_event is more clear?

[nhiroki, 2017/02/09 05:11:32]

Done.

+
+self.addEventListener('install', e => {
+  var scope = new URL(self.registration.scope);
+  if (scope.searchParams.get('type') == 'features-during-install') {
+    internals.countFeature(scope.searchParams.get('feature'));
+    internals.countDeprecation(scope.searchParams.get('deprecated'));
+  } else if (scope.searchParams.get('type') == 'skip-waiting') {
+    e.waitUntil(self.skipWaiting());
+  }
+  run_install_event = true;
+});
+
+onmessage = e => {
+  if (e.data.type == 'COUNT_FEATURE') {
+    internals.countFeature(e.data.feature);
+    e.source.postMessage({type: 'COUNTED'});
+  } else if (e.data.type == 'COUNT_DEPRECATION') {
+    internals.countDeprecation(e.data.feature);
+    e.source.postMessage({type: 'COUNTED'});
+  } else if (e.data.type == 'CLAIM') {
+    let promise = self.clients.claim()
+        .then(() => e.source.postMessage(
+            {type: 'CLAIMED', restarted: !run_install_event}));
+    e.waitUntil(promise);
+  }
+};