Added restart_in_chroot_if_needed to common.sh.

Added restart_in_chroot_if_needed to common.sh.

Add restart_in_chroot_if_needed to common.sh, and modify the build scripts which referred to assert_inside_chroot to use it instead. The effect is that you don't ever have to explicitly enter_chroot.sh to build (still can, it work's fine).

Update mod_image_for_test.sh to use restart_in_chroot_if_needed

[sosa, 2010-05-01 00:35:14]

Overall this looks good, but some scripts outside the chroot call scripts by
absolute path.  Unfortuantely the absolute path isn't the same in/outside the
chroot.  Take for example, archived_build.sh that the buildbot calls (will fail
atm with this change).  You need to update any scripts that call these scripts
and do so by absolute path.

http://codereview.chromium.org/1736025/diff/2001/3004
File src/scripts/common.sh (right):

http://codereview.chromium.org/1736025/diff/2001/3004#newcode1
src/scripts/common.sh:1: 
Remove blank line

[dgarrett, 2010-05-03 20:58:36]

This change should have no effect unless you are trying to do something that
would have failed previously, so I don't think it will break any existing
wrapper scripts.

However, you are correct when you say that invoking a script via absolute paths
will break my function. Is it safe to assume that any script including common.sh
will live in src/scripts?

[dgarrett, 2010-05-03 21:47:51]

Would this be an appropriate fix?

    # Equivalent to enter_chroot.sh -- <current command>
    exec $SCRIPTS_DIR/enter_chroot.sh -- \
      $CHROOT_TRUNK_DIR/src/scripts/$(basename $0) $*

[sosa, 2010-05-03 21:55:27]

Yes I think so.  In this CL can you take the logic out for mod_image_for_test. 
I'll re-add if I can get it work.  The problem atm is it only sort of works both
in and outside chroot (i.e. has errors but doesn't fail so that needs to be
fixed first)

[sosa, 2010-05-04 22:52:56]

lgtm