Pass the context from which a given receiver is accessed explicitly

Pass the context from which a given receiver is accessed explicitly

This will allow for probing access from any context to any receiver in a
future CL.

BUG=none
R=jkummerow@chromium.org,verwaest@chromium.org
LOG=n

Committed: https://crrev.com/5e47350645b912ab2b804309922bbd252e30332e
Cr-Commit-Position: refs/heads/master@{#31196}

[jochen (gone - plz use gerrit), 2015-10-09 13:03:42]

ptal

no functional change (intended)

[Jakob Kummerow, 2015-10-09 13:08:57]

lgtm

[jochen (gone - plz use gerrit), 2015-10-09 13:09:38]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2015-10-09 13:09:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398093002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398093002/1

[commit-bot: I haz the power, 2015-10-09 13:25:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-09 13:26:04]

Patchset 1 (id:??) landed as
https://crrev.com/5e47350645b912ab2b804309922bbd252e30332e
Cr-Commit-Position: refs/heads/master@{#31196}