Fix example bug: compile error

Author: jianghan <jianghan@xiaomi.com>

Closes #132 from pooorman/master and squashes the following commits:

54afbe0 [jianghan] Fix example bug: compile error
(cherry picked from commit 31a704004f9b4ad34f92ae5c95ae6e90d0ab62c7)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>