Use absolute path to chrome_set_ver.
Use absolute path to chrome_set_ver.

So that users don't need to run gclient to update depot_tools when they
are developing for chrome in the chroot (i.e., using cros_workon and
emerge), since they don't need to run chrome_set_ver manually.

Developing for chrome outside of the chroot (running 'make' by
themselves) still requires the user to run chrome_set_ver manually after
a repo sync.  So they also need to run gclient to get the chrome_set_ver
symlink.

BUG=chromium-os:19112
TEST=ran cros_workon start chromeos-chrome

Change-Id: I93a6db4930ccacfa859d83d8fb19ec45b594dd31
Reviewed-on: http://gerrit.chromium.org/gerrit/6201
Reviewed-by: Zdenek Behan <483cf2a9a4e071d4fd973db6a5a78c40f490667c@chromium.org>
Tested-by: Ryan Cui <5ce1592d53754a87a44fc2eb7b63d5f77cf50fdb@chromium.org>

mgireesh05/dev-util,mgireesh05/dev-util,coreos/dev-util,marineam/coreos-dev-util,mgireesh05/dev-util,coreos/dev-util,marineam/coreos-dev-util,coreos/dev-util