Initial in-process implementation of some Mojo primitives.

This has an initial in-process implementation of the most basic Mojo primitives:
  - MojoClose()
  - MojoWait()
  - MojoWaitMany()
  - MojoCreateMessagePipe()
  - MojoWriteMessage()
  - MojoReadMessage()

R=darin@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=225801

Review URL: https://codereview.chromium.org/23621056

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225821 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225821