service worker: Implement NavigationPreloadManager.getState

third_party/WebKit/LayoutTests/http/tests/serviceworker/navigation-preload/resources/get-state-worker.js

Index: third_party/WebKit/LayoutTests/http/tests/serviceworker/navigation-preload/resources/get-state-worker.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/serviceworker/navigation-preload/resources/get-state-worker.js b/third_party/WebKit/LayoutTests/http/tests/serviceworker/navigation-preload/resources/get-state-worker.js
new file mode 100644
index 0000000000000000000000000000000000000000..93ee461c10d9bb1c2cff5f84ebb314844b89f3e8
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/http/tests/serviceworker/navigation-preload/resources/get-state-worker.js
@@ -0,0 +1,19 @@
+// This worker listens for commands from the page and messages back
+// the result.
+
+function handle(message) {
+  const np = self.registration.navigationPreload;
+  switch (message) {
+    case 'getState':
+      return np.getState();
+    case 'enable':
+      return np.enable();
+    case 'disable':
+      return np.disable();
+  }
+  return Promise.reject('bad message');
+}
+
+self.addEventListener('message', e => {
+    e.waitUntil(handle(e.data).then(result => e.source.postMessage(result)));
+  });