Disable tcmalloc sampling by default.
Disable tcmalloc sampling by default.

It's not performance critical, but it allocates some
additional amount of memory on sampled allocations 
which we probably do not want.

[This is really http://codereview.chromium.org/385105
written by antonm, and I'm just landing it.]


r=antonm,willchan
Review URL: http://codereview.chromium.org/401012

git-svn-id: http://src.chromium.org/svn/trunk/src@32329 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 74936a12c0bb79a0820d5ff830f9566e9cdf4231
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser