Pass the final URL an app was loaded from to the app in Initialize().

mojo/public/cpp/application/lib/application_test_base.cc

Index: mojo/public/cpp/application/lib/application_test_base.cc
diff --git a/mojo/public/cpp/application/lib/application_test_base.cc b/mojo/public/cpp/application/lib/application_test_base.cc
index ba6dd3f0ca0e7ae7d6357b3d62f1729e34ad5282..d4e002f74ffcc66de774d7c8ccbe4085e0115463 100644
--- a/mojo/public/cpp/application/lib/application_test_base.cc
+++ b/mojo/public/cpp/application/lib/application_test_base.cc
@@ -47,7 +47,9 @@ class ShellAndArgumentGrabber : public Application {
 
  private:
   // Application implementation.
-  void Initialize(ShellPtr shell, Array<String> args) override {
+  void Initialize(ShellPtr shell,
+                  Array<String> args,
+                  const mojo::String& url) override {
     *args_ = args.Pass();
     g_application_request = binding_.Unbind();
     g_shell = shell.Pass();
@@ -137,7 +139,7 @@ void ApplicationTestBase::SetUp() {
                                           g_application_request.Pass());
 
   // Fake application initialization with the given command line arguments.
-  application_impl_->Initialize(g_shell.Pass(), g_args.Clone());
+  application_impl_->Initialize(g_shell.Pass(), g_args.Clone(), "");
 }
 
 void ApplicationTestBase::TearDown() {