Rename Thread -> OSThread.

Rename Thread -> OSThread.

It's a collection of static utility methods for primitive operations on OS threads.

Make room in the namespace for upcoming class that will represent all the complex state of a VM thread.

Committed: https://code.google.com/p/dart/source/detail?r=42895

[koda, 2015-01-14 19:33:54]

I probably also want to rename the thread.h and thread_linux.{h,cc} etc. files.

Maybe "synchronization", "os_threads", or "os_threading" (indicating they are
mainly abstraction layers).

[siva, 2015-01-15 01:17:30]

I was wondering why not we rename it to OSThread instead
of ThreadUtils. ThreadUtils sounds like a bunch of utilities on threads not core
Thread functionality.

[koda, 2015-01-15 02:23:16]

On 2015/01/15 01:17:30, siva wrote:
> I was wondering why not we rename it to OSThread instead
> of ThreadUtils. ThreadUtils sounds like a bunch of utilities on threads not
core
> Thread functionality.

OSThread is fine with me.

I've now also renamed the corresponding files and updated all references to them
(both computer- and human-readable).

[koda, 2015-01-15 02:30:25]

Committed patchset #7 (id:120001) manually as r42895 (presubmit successful).