Mojo: Add a Mojo-specific multiprocess test base class.

This sets up (most of) the infrastructure that'll be needed to set up a
PlatformChannel between parent and child processes.

[email protected], darin

Review URL: https://codereview.chromium.org/99473007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238425 0039d316-1c4b-4281-b951-d872f2087c98
6 files changed