Fix StatsCounters on mac.

Fix StatsCounters on mac.

In order for the shared memory to work, they must all use the same file name
which is keyed by the pid of the browser process. Previously the mac code path
was using the pid for each process so there was no sharing happening. Now mac
uses the same code path as win which properly uses the parent pid for all procs.

BUG=None
TEST=None

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=72538

[tonyg, 2011-01-24 23:56:55]

http://codereview.chromium.org/6364006/diff/1/chrome/app/chrome_main.cc
File chrome/app/chrome_main.cc (left):

http://codereview.chromium.org/6364006/diff/1/chrome/app/chrome_main.cc#oldco...
chrome/app/chrome_main.cc:768: #if defined(OS_MACOSX)
FYI, this is no functional change. I just noticed it is redundant since it is
already embedded in a defined(OS_MACOSX) guard.

[Mike Belshe, 2011-01-25 18:55:19]

lgtm!