service worker: Deflake fetch-event.https.html.

The test was using add_result_callback() which is triggered after a test
finishes. Unfortunately this file uses both async_test and promise_test.
promise_tests run sequentially but async_tests run in parallel. Therefore,
the add_result_callback was being called every time an async_test finished,
causing a race when this promise_test was in the middle of execution.

R=shimazu

Bug: 807014
Change-Id: Ic1bc568fe812f540feec901f95cc89684ef1cae2
Reviewed-on: https://chromium-review.googlesource.com/892553Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532758}

third_party/WebKit/LayoutTests/TestExpectations

@@ -649,13 +649,9 @@ crbug.com/538697 [ Win ] printing/webgl-oversized-printing.html [ Failure Crash
 # Found 2061 tests; running 2060, skipping 1.
 # 2060 tests ran as expected (1968 passed, 92 didn't).
 
-# The outofblink-cors version of fetch-event.https.html, below, is also timeout-flaky.
-crbug.com/807014 external/wpt/service-workers/service-worker/fetch-event.https.html [ Pass Timeout ]
-crbug.com/807014 virtual/service-worker-script-streaming/external/wpt/service-workers/service-worker/fetch-event.https.html [ Pass Timeout ]
-
 # Crashing tests in dictionary order.
 crbug.com/736308 virtual/outofblink-cors/external/wpt/service-workers/service-worker/fetch-cors-xhr.https.html [ Failure Crash ]
-crbug.com/736308 virtual/outofblink-cors/external/wpt/service-workers/service-worker/fetch-event.https.html [ Crash Timeout ]
+crbug.com/736308 virtual/outofblink-cors/external/wpt/service-workers/service-worker/fetch-event.https.html [ Crash ]
 crbug.com/736308 virtual/outofblink-cors/external/wpt/service-workers/service-worker/fetch-event-network-error.https.html [ Crash ]
 crbug.com/736308 virtual/outofblink-cors/external/wpt/service-workers/service-worker/fetch-request-fallback.https.html [ Crash Failure ]
 crbug.com/736308 virtual/outofblink-cors/external/wpt/service-workers/service-worker/fetch-request-redirect.https.html [ Crash ]

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https.html

@@ -197,7 +197,7 @@ function submit_form(action_url) {
       form.appendChild(input2);
       document.body.appendChild(form);
       frame.onload = function() {
-        document.body.removeChild(form);
+        form.remove();
         resolve(frame);
       };
       form.submit();
@@ -206,9 +206,11 @@ function submit_form(action_url) {
 
 promise_test(t => {
     const scope = 'resources/simple.html?form-post';
+    let registration;
     return service_worker_unregister_and_register(t, worker, scope)
       .then(reg => {
-          add_result_callback(() => { reg.unregister(); });
+          registration = reg;
+          add_completion_callback(() => { reg.unregister(); });
           return wait_for_state(t, reg.installing, 'activated');
         })
       .then(() => {
@@ -219,15 +221,18 @@ promise_test(t => {
                         'POST:application/x-www-form-urlencoded:' +
                         'testName1=testValue1&testName2=testValue2');
           frame.remove();
+          return registration.unregister();
         });
   }, 'Service Worker responds to fetch event with POST form');
 
 promise_test(t => {
     // Add '?ignore' to scope so the service worker falls back to network.
     const scope = 'resources/echo-content.py?ignore';
+    let registration;
     return service_worker_unregister_and_register(t, worker, scope)
       .then(reg => {
-          add_result_callback(() => { reg.unregister(); });
+          registration = reg;
+          add_completion_callback(() => { reg.unregister(); });
           return wait_for_state(t, reg.installing, 'activated');
         })
       .then(() => {
@@ -237,6 +242,7 @@ promise_test(t => {
           assert_equals(frame.contentDocument.body.textContent,
                         'testName1=testValue1&testName2=testValue2');
           frame.remove();
+          return registration.unregister();
         });
   }, 'Service Worker falls back to network in fetch event with POST form');