Simple multi-url support for mojo apps

mojo/tools/data/apptests

 # This file contains a list of Mojo gtest unit tests.
 # This must be valid python. It can use the |config| global that will be a
 # mopy.config.Config object and must set a |tests| global that will contain the
 # tests to run.
 # TODO(vtl|msw): Add a way of specifying data dependencies.
 
 tests = [
   {
     "test": "mojo:clipboard_apptests",
   },
@@ skipping 12 matching lines @@
     "test": "mojo:mojo_view_manager_client_apptests",
     "shell-args": ["--args-for=mojo:native_viewport_service --use-headless-config --use-osmesa"],
   },
   {
     "test": "mojo:view_manager_service_apptests",
     "shell-args": ["--args-for=mojo:native_viewport_service --use-headless-config --use-osmesa"],
   },
   {
     "test": "mojo:window_manager_apptests",
   },
+  {
+    "test": "mojo:shell_apptests",
+  },
 ]
 
 if config.target_os == config.OS_LINUX:
   tests += [
     {
       "test": "mojo:example_apptests",
       # ExampleApplicationTest.CheckCommandLineArg checks --example_apptest_arg.
       "test-args": ["--example_apptest_arg"],
       "shell-args": [
         "--url-mappings=mojo:example_service=mojo:python_example_service"
@@ skipping 30 matching lines @@
     {
       "test": "mojo:js_apptests",
     },
     {
       "test": "mojo:reaper_apptests",
     },
     {
       "test": "mojo:dart_apptests",
     },
   ]