Introduce SetName and SetDiscoverable functions to BluetoothAdapter.

These patch only implements these functions for ChromeOS.

BUG=332938
TEST=new unit tests

Review URL: https://codereview.chromium.org/156923003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249917 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249917