Reland of land #2 of Enable whitelist generation for official builds.

Reland of land #2 of Enable whitelist generation for official builds. (patchset #1 id:1 of https://codereview.chromium.org/2277523002/ )

Reason for revert:
want to test that manual tryjob can be used to detect next failure.

Original issue's description:
> Revert of Reland #2 of Enable whitelist generation for official builds. (patchset #2 id:20001 of https://codereview.chromium.org/2271673002/ )
> 
> Reason for revert:
> Breaking perf try bot https://build.chromium.org/p/tryserver.chromium.perf/builders/android_perf_bisect_builder/builds/14535/steps/compile/logs/stdio
> 
> Original issue's description:
> > Reland #2 of Enable whitelist generation for official builds.
> >
> > Previous: https://codereview.chromium.org/2241383004/
> >
> > Currently, all resources are included in PAK files when Chrome is
> > built locally. Only official_buildbot.sh uses a resource whitelist. This CL
> > enables local builds to use resource whitelisting by setting the
> > enable_resource_whitelist_generation gn flag to true, or by building an
> > official build.
> >
> > This will allow developers to more easily monitor the changes in APK size
> > for each commit they make.
> >
> > However, a large amount of output is generated (_pragma is used to
> > create warnings to allow whitelisted resources to be listed), so for now
> > the whitelist will only be generated for official builds.
> >
> > This change results in a ~1.5 mb difference when calculating the APK size with resource_sizes.py.
> >
> > BUG=632385
> >
> > Committed: https://crrev.com/c7e6104c8c2ed8080115e92ff3c6f9d748e7feae
> > Cr-Commit-Position: refs/heads/master@{#413794}
> 
> TBR=agrieve@chromium.org,dpranke@chromium.org,estevenson@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=632385
> 
> Committed: https://crrev.com/e925fbcc80e35d175d10b72be9c544f89c1bf5f1
> Cr-Commit-Position: refs/heads/master@{#413860}

TBR=dpranke@chromium.org,estevenson@chromium.org,pkotwicz@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=632385

[agrieve, 2016-08-24 03:46:52]

Created Reland of land #2 of Enable whitelist generation for official builds.

[Dirk Pranke, 2016-08-24 15:25:14]

lgtm