Rename kPinnedAppsPrefAppIDPath to kPinnedAppsPrefAppIDKey

To be consistent with usage of base::Value::SetKey (as opposed to
base::Value::SetPath).

Bug: none
Change-Id: I07648205e14cb17a22409d11cd5d3737f53e01e8
Reviewed-on: https://chromium-review.googlesource.com/c/1449577
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Pavol Marko <pmarko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629918}
6 files changed