GN Command line -D parsing, goma on Windows

GN Command line -D parsing, goma on Windows

This makes gyp_chromium pass defines defined via -D on the command line to GN.

Fixes double-escaping of strings from supplemental.gypi files.

Pass use_goma to the GN build.

Handle "use_goma" and "use_goma=1" (same for other boolean values). Previously values with no equals sign were getting converted to 'true', which doesn't match '1' which we look for.

Output goma wrappers in the GYP header for Windows toolchains.

R=scottmg@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=243446

[scottmg, 2014-01-06 22:10:15]

lgtm

[commit-bot: I haz the power, 2014-01-07 00:57:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brettw@chromium.org/123463005/110001

[commit-bot: I haz the power, 2014-01-07 11:01:45]

Retried try job too often on mac_rel for step(s) app_list_unittests,
base_unittests, browser_tests, cacheinvalidation_unittests, cc_unittests,
check_deps, check_deps2git, chromedriver_unittests, components_unittests,
content_browsertests, content_unittests, crypto_unittests,
google_apis_unittests, gpu_unittests, interactive_ui_tests, ipc_tests,
jingle_unittests, media_unittests, message_center_unittests, nacl_integration,
net_unittests, ppapi_unittests, printing_unittests, remoting_unittests,
sql_unittests, sync_integration_tests, sync_unit_tests, telemetry_unittests,
unit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

[brettw, 2014-01-08 00:32:22]

Committed patchset #2 manually as r243446 (presubmit successful).

[Nico, 2014-01-08 19:21:24]

This broke building on OS X and is blocking me from work
(http://crbug.com/332458). Unless there's an easy, quick fix this should
probably be reverted for now.