Do not start goma in ChromeOS gclient runhook if gomadir is given.

scripts/slave/recipe_modules/chromium/api.py

Index: scripts/slave/recipe_modules/chromium/api.py
diff --git a/scripts/slave/recipe_modules/chromium/api.py b/scripts/slave/recipe_modules/chromium/api.py
index 56759ccd142e979005fce95c549c6466bbe5db0f..5b2cc9fefd6276996492327f74536c4a93e7592d 100644
--- a/scripts/slave/recipe_modules/chromium/api.py
+++ b/scripts/slave/recipe_modules/chromium/api.py
@@ -474,6 +474,7 @@ class ChromiumApi(recipe_api.RecipeApi):
       wrapper += ['--clear-sdk-cache']
     if self.c.compile_py.goma_dir:
       wrapper += ['--gomadir', self.c.compile_py.goma_dir]
+      wrapper += ['--nostart-goma']

[dnj, 2016/09/08 16:14:45]

Can you add a comment here detailing why this flag is added? The "--gomadir" one
is obvious, but "--nostart-goma" is a little less so.

As an aside, why don't we just make it so that "chrome-sdk" is smart enough to
not start goma when "--gomadir" is provided? Is there ever a situation where
"--gomadir" will be supplied and we actually want it to start Goma? From this CL
description, it sounds like the answer is, "no".

[Yoshisato Yanagisawa, 2016/09/12 01:55:11]

Wrote a comment.

I do not know a situation where "--gomadir" is supplied and we actually want it
start goma.  However, I am not confident to say no.
Then, it comes to me the question, "Is it natural to skip starting goma if
--gomadir is set?"  I can hardly say yes.  It looks like the flag to mention
which goma directory to use but it might not look like a flag to change anything
else.  Let me make the script have --nostart-goma.

     if self.c.gyp_env.GYP_DEFINES.get('fastbuild', 0) == 1:
       wrapper += ['--fastbuild']
     wrapper += ['--']