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

examples/content_handler_demo/content_handler_demo.cc

Index: examples/content_handler_demo/content_handler_demo.cc
diff --git a/examples/content_handler_demo/content_handler_demo.cc b/examples/content_handler_demo/content_handler_demo.cc
index 8b17c69e1c1cd843b4c121933b81c0c4409416ef..67b3a66fb7d8aa144e3f8784df1391115c51204f 100644
--- a/examples/content_handler_demo/content_handler_demo.cc
+++ b/examples/content_handler_demo/content_handler_demo.cc
@@ -21,7 +21,9 @@ class PrintBodyApplication : public Application {
                        ScopedDataPipeConsumerHandle body)
       : binding_(this, request.Pass()), body_(body.Pass()) {}
 
-  virtual void Initialize(ShellPtr shell, Array<String> args) override {
+  virtual void Initialize(ShellPtr shell,
+                          Array<String> args,
+                          const mojo::String& url) override {
     shell_ = shell.Pass();
   }
   virtual void RequestQuit() override {}