Revert 109903 - Revert 109898 - Set the profiler's thread name at a central place

Revert 109903 - Revert 109898 - Set the profiler's thread name at a central place

[I've removed the code, via a separate CL, that DCHECK() earlier today]

This will automatically catch thread names in several of the
child processes we are after, and it also catches the name
for a webkcore thread.

r=rtenneti
Review URL: http://codereview.chromium.org/8558003

TBR=jar@chromium.org
Review URL: http://codereview.chromium.org/8564014

TBR=jar@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=109962