Get rid of {Run,Terminate}MainApplication(), and more ApplicationDelegate conversion.

examples/echo/echo_client.cc

Index: examples/echo/echo_client.cc
diff --git a/examples/echo/echo_client.cc b/examples/echo/echo_client.cc
index beef9c11bbb12bb73a62006f7d348dd3fc679a5f..0c3383d682bf014a62dab1447d926abf08ccde29 100644
--- a/examples/echo/echo_client.cc
+++ b/examples/echo/echo_client.cc
@@ -38,5 +38,5 @@ class EchoClientApp : public ApplicationImplBase {
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::examples::EchoClientApp echo_client_app;
-  return mojo::RunMainApplication(application_request, &echo_client_app);
+  return mojo::RunApplication(application_request, &echo_client_app);
 }