http://codereview.chromium.org/147084...

http://codereview.chromium.org/147084

Implements unique client ID generation for Posix.

Client ID generation happens once-per-install of Chromium (...well, this is
mostly true, at least).  On Windows, the code currently uses some system library
code that generates a GUID.  We don't ACTUALLY need a GUID, something that's
quite random and in the same format will work.  Since we don't want to add a
dependency on libuuid for POSIX, I created a less-random-but-still-good-enough
version.

BUG=15418
TEST=none


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=20184