Updates DCHECK in mojo/runner/context.cc to match reality
Updates DCHECK in mojo/runner/context.cc to match reality

Needs to be updated now that we honor single-process.

BUG=none
TEST=none
R=jam@chromium.org

Review URL: https://codereview.chromium.org/1615253003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#371051}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk