gyp_chromium integration for automatic toolchain

gyp_chromium integration for automatic toolchain

When opting in via GYP_MSVS_USE_SYSTEM_TOOLCHAIN=0, set
environment variables that tell gyp how to find the automatic
toolchain in third_party/win_toolchain.

R=maruel@chromium.org
BUG=323300
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=238426

[M-A Ruel, 2013-12-03 13:44:56]

lgtm with style nits

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium
File build/gyp_chromium (right):

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium#newco...
build/gyp_chromium:158: if sys.platform in ('win32', 'cygwin') and \
Use () instead of \

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium#newco...
build/gyp_chromium:179: os.environ['GYP_DEFINES'] = ' '.join(['%s=%s' % (k,
pipes.quote(str(v)))
Remove [], it's unnecessary to serialize a generator into a list.

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium#newco...
build/gyp_chromium:181: print 'Using automatic toolchain in %s.' % toolchain
print('Using automatic toolchain in %s.' % toolchain)
generates python 3 ready code (only half-kidding)

[scottmg, 2013-12-03 17:42:02]

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium
File build/gyp_chromium (right):

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium#newco...
build/gyp_chromium:158: if sys.platform in ('win32', 'cygwin') and \
On 2013/12/03 13:44:56, M-A Ruel wrote:
> Use () instead of \

Done. (Was following local style above)

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium#newco...
build/gyp_chromium:179: os.environ['GYP_DEFINES'] = ' '.join(['%s=%s' % (k,
pipes.quote(str(v)))
On 2013/12/03 13:44:56, M-A Ruel wrote:
> Remove [], it's unnecessary to serialize a generator into a list.

Done.

https://codereview.chromium.org/100613002/diff/40001/build/gyp_chromium#newco...
build/gyp_chromium:181: print 'Using automatic toolchain in %s.' % toolchain
On 2013/12/03 13:44:56, M-A Ruel wrote:
> print('Using automatic toolchain in %s.' % toolchain)
> generates python 3 ready code (only half-kidding)

Done. (so ugly!)

[scottmg, 2013-12-03 17:48:34]

Committed patchset #4 manually as r238426 (presubmit successful).