Reland of Pipe response_time from FetchManager to CacheStorage and ServiceWorkerURLRequestJob.

content/test/data/service_worker/fetch_event_response_via_cache.js

+// Copyright 2016 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.
+
+this.onfetch = function(event) {
+    var CACHE_NAME = 'cache_name';
+    var cache = undefined;
+    var url = event.request.url;
+    event.respondWith(
+        caches.open(CACHE_NAME)
+          .then(function(c) {
+              cache = c;
+              return cache.match(url);
+            })
+          .then(function(response) {
+              if (response)
+                return response;
+              var cloned_response = undefined;
+              return fetch(url)
+                .then(function(res) {
+                    cloned_response = res.clone();
+                    return cache.put(url, res);
+                  })
+                .then(function() {
+                    return cloned_response;
+                  });
+            }));
+  };