Get service process running standalone on the mac by hooking it into launchd.

BUG=NONE
TEST=BUILD

Review URL: http://codereview.chromium.org/6482016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@75893 0039d316-1c4b-4281-b951-d872f2087c98

• DEPS[diff]
• base/process_util.h[diff]
• base/process_util_mac.mm[diff]
• base/process_util_posix.cc[diff]
• base/process_util_unittest.cc[diff]
• chrome/browser/service/service_process_control.cc[diff]
• chrome/browser/service/service_process_control.h[diff]
• chrome/browser/service/service_process_control_browsertest.cc[diff]
• chrome/browser/service/service_process_control_mac.mm[Added - diff]
• chrome/chrome_browser.gypi[diff]
• chrome/chrome_common.gypi[diff]
• chrome/common/service_process_util.cc[diff]
• chrome/common/service_process_util.h[diff]
• chrome/common/service_process_util_linux.cc[Added - diff]
• chrome/common/service_process_util_mac.mm[Added - diff]
• chrome/common/service_process_util_posix.cc[diff]
• chrome/common/service_process_util_posix.h[Added - diff]
• chrome/common/service_process_util_unittest.cc[diff]
• chrome/common/service_process_util_win.cc[diff]
• chrome/service/service_ipc_server.cc[diff]
• chrome/service/service_ipc_server.h[diff]
• chrome/service/service_process.cc[diff]
• chrome/service/service_process.h[diff]
• ipc/ipc_channel_posix.cc[diff]