Run GN as part of runhooks.

Run GN as part of runhooks.

This runs GN in GYP mode before actually running GYP.

Currently, GN does not produce any files used by the build, these will be added in a second step.

BUG=
R=maruel@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=236542

[M-A Ruel, 2013-11-14 23:23:36]

https://codereview.chromium.org/62803003/diff/1/build/gyp_chromium
File build/gyp_chromium (right):

https://codereview.chromium.org/62803003/diff/1/build/gyp_chromium#newcode81
build/gyp_chromium:81: 
2 lines between file level symbols

https://codereview.chromium.org/62803003/diff/1/build/gyp_chromium#newcode87
build/gyp_chromium:87: source_root =
os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
It's highly preferable to create a global variable, e.g.
SRC_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
at the module level otherwise any os.chdir() call will invalidate the code here.

https://codereview.chromium.org/62803003/diff/1/build/gyp_chromium#newcode106
build/gyp_chromium:106: 
2 lines

[brettw, 2013-11-14 23:35:11]

PTAL, new snap up.

[M-A Ruel, 2013-11-14 23:40:09]

lgtm

https://codereview.chromium.org/62803003/diff/160001/build/gyp_chromium
File build/gyp_chromium (right):

https://codereview.chromium.org/62803003/diff/160001/build/gyp_chromium#newco...
build/gyp_chromium:112: args = sys.argv[1:]
Going all the code after this line at module level is really wrong, but that's
out of scope of this CL.

[brettw, 2013-11-21 17:36:25]

Committed patchset #3 manually as r236542 (presubmit successful).