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

examples/audio_play_test/play_tone.cc

Index: examples/audio_play_test/play_tone.cc
diff --git a/examples/audio_play_test/play_tone.cc b/examples/audio_play_test/play_tone.cc
index ccbab467ccc4fab53e44336466eb46ba1cae5b02..2407fd9112ee033d96b26123ae2e9d4b86456a69 100644
--- a/examples/audio_play_test/play_tone.cc
+++ b/examples/audio_play_test/play_tone.cc
@@ -243,5 +243,5 @@ void PlayToneApp::Shutdown() {
 
 MojoResult MojoMain(MojoHandle app_request) {
   mojo::media::audio::examples::PlayToneApp play_tone_app;
-  return mojo::RunMainApplication(app_request, &play_tone_app);
+  return mojo::RunApplication(app_request, &play_tone_app);
 }