Improve jni_generator sample documentation.

Add details of C++ registration, build file modifications.

Review URL: https://codereview.chromium.org/1123343005

Cr-Commit-Position: refs/heads/master@{#330944}


CrOS-Libchrome-Original-Commit: d56b07e289ef5e9907587337108b6c8e5ff8c3c8
3 files changed
tree: 47c46c5796a770730424e126fafc178ad025ac29
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/