Reland #317760 - add gn_all, gyp_all targets

Reland #317760 - add gn_all, gyp_all targets

In order to be able to make sure we are building the same list of targets
in both the GYP and GN builds, this patch adds new 'gn_all' and 'gyp_all'
targets.

Eventually, we should make sure that if one builds 'gn_all', then building
'gyp_all', 'All', or 'all' then has nothing to do. We're not there yet, but this
is a start.

The 'gn_all' target replaces the //:root target in the GN builds.

TBR=brettw@chromium.org
BUG=461019
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Committed: https://crrev.com/e2ef382dd208417056acbd579620a428fa1b7af4
Cr-Commit-Position: refs/heads/master@{#317893}

[Dirk Pranke, 2015-02-24 19:33:55]

The fix is to remove views_unittests and wm_unittests on the Mac builds, as well
as removing a reference to a GN-only ozone target.

The Mac failures weren't caught on the trybots because analyze.py didn't include
them, but the main builder builds 'all', so it exploded.

[Dirk Pranke, 2015-02-24 19:34:01]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2015-02-24 19:34:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/953463003/20001

[commit-bot: I haz the power, 2015-02-24 19:56:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-02-24 19:56:50]

Try jobs failed on following builders:
  android_chromium_gn_compile_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[Dirk Pranke, 2015-02-24 20:19:25]

The CQ bit was checked by dpranke@chromium.org

[commit-bot: I haz the power, 2015-02-24 20:20:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/953463003/40001

[commit-bot: I haz the power, 2015-02-24 21:42:31]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-24 21:43:17]

Patchset 3 (id:??) landed as
https://crrev.com/e2ef382dd208417056acbd579620a428fa1b7af4
Cr-Commit-Position: refs/heads/master@{#317893}