Fix slow sound init in piano sample app
Fix slow sound init in piano sample app

Fixes #1696. Also fixes handles leaking on error.

Hixie/flutter,tvolkert/flutter,Hixie/flutter,turnidge/flutter,Hixie/flutter,cbracken/flutter,flutter/flutter,flutter/flutter,aghassemi/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,jason-simmons/flutter,turnidge/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,jason-simmons/flutter,flutter/flutter,tvolkert/flutter,cbracken/flutter,cbracken/flutter,tvolkert/flutter,jason-simmons/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,aghassemi/flutter,tvolkert/flutter,turnidge/flutter,Hixie/flutter,flutter/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,flutter/flutter,turnidge/flutter,Hixie/flutter,Hixie/flutter,cbracken/flutter,aghassemi/flutter,aghassemi/flutter,jason-simmons/flutter,flutter/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,tvolkert/flutter,tvolkert/flutter,turnidge/flutter