Fetch last change (revision) info in a separate action that can run...

Fetch last change (revision) info in a separate action that can run
every build, instead of having it occur as a side effect of updating
some other target for which we want to use normal up-to-date checks.
BUG=none
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=17634

[sgk, 2009-06-03 23:04:50]

This is for preliminary comments (although it does pass on the try servers).

This isolates the SCM revision extraction in a separate target that would run
every build (using a separate .py script), updating the LASTCHANGE file with
just that info. 

We need to do this because, on Windows, this sort of run-every-time thing can't
be an action within another target (e.g. chrome_dll, as it is now) without
causing that target to get rebuilt every time.

Linux currently builds version info in a module in base/, and Windows currently
builds it in a chrome/ resource file.  This draft puts LASTCHANGE extraction in
its own new build/util/build_util.gyp file that both can use.

Once we hammer out a general approach that meets everyone's approval, follow-on 
CLs would look at getting rid of the duplicate version-info-generation code
between Linux and Windows.

[M-A Ruel, 2009-06-04 00:24:28]

lgtm

http://codereview.chromium.org/118192/diff/1001/1003
File build/util/lastchange.py (right):

http://codereview.chromium.org/118192/diff/1001/1003#newcode112
Line 112: opts, args = getopt.getopt(argv[1:], short_options, long_options)
nit: optparser is much cleaner

http://codereview.chromium.org/118192/diff/1001/1003#newcode129
Line 129: sys.stderr.write('Use -h to get help.')
\n

[sgk, 2009-06-04 00:52:54]

http://codereview.chromium.org/118192/diff/1001/1003
File build/util/lastchange.py (right):

http://codereview.chromium.org/118192/diff/1001/1003#newcode129
Line 129: sys.stderr.write('Use -h to get help.')
On 2009/06/04 00:24:28, M-A wrote:
> \n

Done.

[sgk, 2009-06-04 01:42:10]

http://codereview.chromium.org/118192/diff/1001/1003
File build/util/lastchange.py (right):

http://codereview.chromium.org/118192/diff/1001/1003#newcode112
Line 112: opts, args = getopt.getopt(argv[1:], short_options, long_options)
On 2009/06/04 00:24:28, M-A wrote:
> nit: optparser is much cleaner

Done (whiling away the time waiting for a green tree...)