Add LayoutTests for mixed range response handling.

LayoutTests/http/tests/serviceworker/chromium/resources/service-worker-mixed-response-worker.js

+importScripts('../../../resources/get-host-info.js');
+
+var HOST_INFO = get_host_info();
+var PARTIAL_RESOURCE_PATH =
+    '/serviceworker/chromium/resources/service-worker-mixed-response.php';
+
+function get_query_params(url) {
+  var search = (new URL(url)).search;
+  if (!search) {
+    return {};
+  }
+  var ret = {};
+  var params = search.substring(1).split('&');
+  params.forEach(function(param) {
+      var element = param.split('=');
+      ret[decodeURIComponent(element[0])] = decodeURIComponent(element[1]);
+    });
+  return ret;
+}
+
+function generate_partial_byte_response(position) {
+  return new Response(
+      'Ogg'.substr(position, 1),
+      {
+        status: 206,
+        headers: {
+          'content-type': 'audio/ogg',
+          // 12983 is the file size of media/content/silence.oga.
+          'content-range': 'bytes ' + position + '-' + position + '/12983'
+        }
+      });
+}
+
+function fetch_same_origin_partial_resource(position) {
+  return fetch(HOST_INFO['HTTP_ORIGIN'] + PARTIAL_RESOURCE_PATH +
+               '?position=' + position)
+}
+
+function fetch_cross_origin_partial_resource(position) {
+  return fetch(HOST_INFO['HTTP_REMOTE_ORIGIN'] + PARTIAL_RESOURCE_PATH +
+               '?position=' + position)
+}
+
+self.addEventListener('fetch', function(event) {
+    if (event.request.url.indexOf('blank.html') != -1) {
+      // The request is for the page load.
+      return;
+    }
+    var params = get_query_params(event.request.url);
+    if (event.request.headers.get('range') == 'bytes=0-') {
+      if (params['SW_FIRST'] == 'gen') {
+        event.respondWith(generate_partial_byte_response(0));
+      } else if (params['SW_FIRST'] == 'same') {
+        event.respondWith(fetch_same_origin_partial_resource(0));
+      } else if (params['SW_FIRST'] == 'cross') {
+        event.respondWith(fetch_cross_origin_partial_resource(0));
+      }
+    } else if (event.request.headers.get('range') == 'bytes=1-') {
+      if (params['SW_SECOND'] == 'gen') {
+        event.respondWith(generate_partial_byte_response(1));
+      } else if (params['SW_SECOND'] == 'same') {
+        event.respondWith(fetch_same_origin_partial_resource(1));
+      } else if (params['SW_SECOND'] == 'cross') {
+        event.respondWith(fetch_cross_origin_partial_resource(1));
+      }
+    }
+  });