Valgrind: Tool changes to support running browser tests with memcheck in sharding_supervisor.

- Add ability to override CPU count in sharding_supervisor via an envvar.
- Add a dummy gtest compatibility flag to the Valgrind test runner script.

BUG=118609
TEST=none
Review URL: https://chromiumcodereview.appspot.com/10417048

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138615 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed