Foreign fetch should not intercept same origin or main resource requests.

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-worker.js

Index: third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-worker.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-worker.js b/third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-worker.js
index 2be0db23f678aff2e48292e309a2efe3361f0d53..765972c71856bafce9298feab5441fe47e62f5af 100644
--- a/third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-worker.js
+++ b/third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/foreign-fetch-worker.js
@@ -1,9 +1,47 @@
 self.addEventListener('install', function(event) {
-    var origins = JSON.parse(decodeURIComponent(location.search.substring(1)));
-    event.registerForeignFetch({scopes: [registration.scope + '/intercept'],
-                                origins: origins});
+    var params = JSON.parse(decodeURIComponent(location.search.substring(1)));
+    if (!('scopes' in params)) {
+      if ('relscopes' in params) {
+        params.scopes = params.relscopes.map(s => registration.scope + s);
+      } else {
+        params.scopes = [registration.scope];
+      }
+    }
+    if (!('origins' in params))
+      params.origins = ['*'];
+    event.registerForeignFetch(params);
   });
 
+function handle_basic(event) {
+  event.respondWith({response:
+    new Response('Foreign Fetch',
+                  {headers: {'Access-Control-Allow-Origin': '*'}})});
+}
+
+function handle_onmessage(event) {
+  event.respondWith({response:
+    new Response('<script>window.onmessage = e => e.ports[0].postMessage("failed");</script>',
+                {headers: {'Content-Type': 'text/html', 'Access-Control-Allow-Origin': '*'}})});
+}
+
 self.addEventListener('foreignfetch', function(event) {
-    event.respondWith({response: new Response('Foreign Fetch')});
+    var url = event.request.url;
+    var handlers = [
+      { pattern: '?basic', fn: handle_basic },
+      { pattern: '?onmessage', fn: handle_onmessage }
+    ];
+
+    var handler = null;
+    for (var i = 0; i < handlers.length; ++i) {
+      if (url.indexOf(handlers[i].pattern) != -1) {
+        handler = handlers[i];
+        break;
+      }
+    }
+
+    if (handler) {
+      handler.fn(event);
+    } else {
+      event.respondWith(new Response('unexpected request'));
+    }
   });