Mojo: re-org public/utility and public/environment

Mojo: re-org public/utility and public/environment

The plan:
- mojo/public/{subdir} contains public headers and scripts (if any).
- mojo/public/{subdir}/lib contains private headers and .cc files (if any).
- mojo/public/{subdir}/tests contains test files.

Also, as part of this CL:

1- I simplified the TLS implementation in utility and hid it as an internal API. I'm not happy providing the API to third-parties as is. It was really intended to be used with LazyInstance, etc. Without that there is some subtlety with setup and teardown of the TLS slot. Hiding it avoids having to deal with this for now.

2- Deleted thread_local_unittest.cc as that was still coded against base/threading/thread_local.h (oops)! Besides that this test has a large dependency on base threading and synchronization primitives. It also isn't that useful to test our wrappers for TLS as they are such thin wrappers around the OS provided APIs.

3- Renamed environment/standalone to environment/lib for consistency. From the point of view of a third-party, lib is the better name for this directory.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=247927

[darin (slow to review), 2014-01-29 21:57:51]

I couldn't get git to recognize that thread_local.h simply moved from utility/
to utility/lib/. Sigh.

[viettrungluu, 2014-01-29 22:11:30]

LGTM (as far as I can tell -- rietveld isn't making it very easy to see what's
going on).

[commit-bot: I haz the power, 2014-01-29 22:14:13]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/darin@chromium.org/148013006/70001

[commit-bot: I haz the power, 2014-01-30 10:41:50]

Change committed as 247927