Add option to deploy Chrome to stateful partition

Flag --mount-dir <mount_dir> allows Chrome to be deployed in target_dir,
specified by --target-dir, and then bind mounted on mount_dir.

Flag --mount puts deploy_chrome in mount state. If no target directory
is specified, it sets to /mnt/stateful_partition/opt/google/chrome;
if no mount directory is specified, it sets it to /opt/google/chrome.

Deploying chrome without --target-dir or the mount flags will still deploy it,
by default, to /opt/google/chrome.

NOTE: As of now, the default mount directory is not created by the script.

TEST=None
BUG=None

Change-Id: I2ed05967cd9e045e0aad8cfcaa537f284282d74c
Signed-off-by: Thiago Goncales <thiagog@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/56490
Reviewed-by: Ryan Cui <rcui@chromium.org>
2 files changed