Rename KeyLock to KeyboardLock and return enum from IPC
This change addresses one remaining work in change
https://codereview.chromium.org/2805763004/ to modify the return value of
RequestKeyLock() mojom interface from (bool, string) to an enumeration.
Meanwhile, after discussing with Gary (GaryKac@), we would prefer to keep
"Keyboard" as part of the function name. So all "KeyLock"s are changed to
"KeyboardLock".
BUG=680809
Review-Url: https://codereview.chromium.org/2852823002
Cr-Commit-Position: refs/heads/master@{#468791}
17 files changed
