WifiNative: make getLocalLog() an instance method

We want to add some tests that mock out WifiNative.getLocalLog().
To do that, we need getLocalLog() to be an instance method.
Make it so.

While there: add @NonNull annotation to getLocalLog(), to
make the semantics clearer.

BUG=29424414
TEST=unit tests

Change-Id: Ifb224104cf54b42a945258967dcaf50541849abc
2 files changed
tree: 6fe4eccac6f51b877f4d4bb2faace2a539e6324e
  1. libwifi_hal/
  2. libwifi_system/
  3. service/
  4. tests/