Add use_goma for GYP_DEFINES

Add use_goma for GYP_DEFINES

If use_goma is specified in GYP_DEFINES, gomacc is automatically set as
CC wrapper and CXX wrapper. It uses the default goma directory if the gomadir
option is not given. No need to fix PATH when running ninja (or make).
This is the revival of https://codereview.chromium.org/69293004/.
In https://codereview.chromium.org/69293004/, I removed ANDROID_GOMA_WRAPPER
code, which is actually used.  This code supports both way of enabling goma
for Android.  You can set GOMA_DIR or you can set -D use_goma=1.

Currently, this works well with ninja (default build system of chromium).
It does not work well with make in some case (e.g. build on linux with make).

Example 1
$ GYP_DEFINES="clang=1 use_goma=1" build/gyp_chromium
(no need to set CC/CXX at this stage)

build.ninja will have
cc = ${HOME}/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang
cxx = ${HOME}/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang++

The user can run ninja without setting PATH or so.
$ ninja -C out/Release -j100

Example 2

$ GYP_DEFINES="use_goma=1 gomadir=/path/to/goma" build/gyp_chromium

build.ninja will have
cc = /path/to/goma/gomacc gcc
cxx = /path/to/goma/gomacc g++

user can run ninja without setting PATH or so.
$ ninja -C out/Release -j100

BUG=173686
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=237900

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=238630

[Yoshisato Yanagisawa, 2013-12-03 02:18:23]

Will you take a look at this change?
And, will you check it won't make "Android Builder" bot upset?

http://build.chromium.org/p/chromium.webkit/builders/Android%20Builder

Thank you in advance,
Yoshisato.

[eae, 2013-12-03 22:05:12]

LGTM, lets see what the android bots thinks of it.

[Yoshisato Yanagisawa, 2013-12-04 01:59:38]

Let me check android_nexus4_perf_bisect fails by this change or not.

[Yoshisato Yanagisawa, 2013-12-04 02:36:57]

On 2013/12/04 01:59:38, yanagisawa wrote:
> Let me check android_nexus4_perf_bisect fails by this change or not.

This change seems not the cause of android_nexus4_perf_bisect error.
It shows the same behavior even without meaningful change.

[Yoshisato Yanagisawa, 2013-12-04 02:38:05]

On 2013/12/04 02:36:57, yanagisawa wrote:
> On 2013/12/04 01:59:38, yanagisawa wrote:
> > Let me check android_nexus4_perf_bisect fails by this change or not.
> 
> This change seems not the cause of android_nexus4_perf_bisect error.
> It shows the same behavior even without meaningful change.

I should note:
Please see Patch Set 5.

[Yoshisato Yanagisawa, 2013-12-04 05:08:14]

Since Android bots looks not failing with this change, let me hit Commit button.

[commit-bot: I haz the power, 2013-12-04 05:08:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yyanagisawa@chromium.org/96923002/100001

[commit-bot: I haz the power, 2013-12-04 07:32:43]

Change committed as 238630

[boliu, 2013-12-04 17:11:39]

One potential fix: https://codereview.chromium.org/104563004/

https://codereview.chromium.org/96923002/diff/100001/build/common.gypi
File build/common.gypi (right):

https://codereview.chromium.org/96923002/diff/100001/build/common.gypi#newcod...
build/common.gypi:112: 'android_goma_dir%': '<!(dirname
"${ANDROID_GOMA_WRAPPER}")',
This is breaking android builds that is *not* using goma. dirname returns . when
given an empty string, and gyp rules assume goma is available:

$ export ANDROID_GOMA_WRAPPER=""
$ dirname "${ANDROID_GOMA_WRAPPER}"
.