Make it possible to pass a default url to sky_debugger

sky/tools/debugger/debugger.h

Index: sky/tools/debugger/debugger.h
diff --git a/sky/tools/debugger/debugger.h b/sky/tools/debugger/debugger.h
index d7412a257e94bed6de64a84aa0ae77a0dda76063..5f8904a4f547f00df657d3486e1a23995622d7cd 100644
--- a/sky/tools/debugger/debugger.h
+++ b/sky/tools/debugger/debugger.h
@@ -69,8 +69,11 @@ class SkyDebugger : public mojo::ApplicationDelegate,
 
   scoped_ptr<window_manager::WindowManagerApp> window_manager_app_;
 
+  // TODO(eseidel): This is per-embedding state and should be separate
+  // from the ApplicationDelegate!
   mojo::View* root_;
   mojo::View* content_;
+  std::string default_url_;
   std::string pending_url_;
 
   mojo::ServiceProviderPtr viewer_services_;