mojo: add some end-to-end shell tests and a new test sample app

mojo/services/test_service/test_service.mojom

Index: mojo/services/test_service/test_service.mojom
diff --git a/mojo/services/test_service/test_service.mojom b/mojo/services/test_service/test_service.mojom
index 1065b20ab30847eca7a74f2ed21f5e31691f6ed4..4ed741e1a38e815887f34963e5f153b0cd8a3797 100644
--- a/mojo/services/test_service/test_service.mojom
+++ b/mojo/services/test_service/test_service.mojom
@@ -4,8 +4,18 @@
 
 module mojo.test {
 
-interface ITestService {
+interface TestService {
   Ping() => ();
+  // Connect to a TestTimeService at |app_url| and ferry the data back
+  // in |response|.
+  ConnectToAppAndGetTime(string app_url) => (int64 time_usec);
+  StartTrackingRequests() => ();
+};
+
+interface TestTimeService {
+  // Provides a constant time value.
+  GetPartyTime() => (int64 time_usec);
+  StartTrackingRequests() => ();
 };
 
 }  // module mojo.test