Enable setting configuration arguments for Mojo applications with mojo_shell

mojo/examples/wget/wget.cc

Index: mojo/examples/wget/wget.cc
diff --git a/mojo/examples/wget/wget.cc b/mojo/examples/wget/wget.cc
index 0f7d891f88f284cde36c195fb02bb2869d6f803c..f7c03bb6af17bdd074ffe400c68b5b371c6fced6 100644
--- a/mojo/examples/wget/wget.cc
+++ b/mojo/examples/wget/wget.cc
@@ -72,12 +72,12 @@ class WGetApp : public ApplicationDelegate {
  public:
   virtual void Initialize(ApplicationImpl* app) override {
     app->ConnectToService("mojo:mojo_network_service", &network_service_);
-    Start();
+    Start(app->args());
   }
 
  private:
-  void Start() {
-    std::string url = PromptForURL();
+  void Start(const Array<String>& args) {
+    std::string url((args.size() > 1) ? args[1].get() : PromptForURL());
     printf("Loading: %s\n", url.c_str());
 
     network_service_->CreateURLLoader(Get(&url_loader_));