GitLab

ObjectProxy's real method calls Bus::AssertOnOriginThread()
and causes in some log spam (but surprisingly doesn't
crash). Override the method in MockObjectProxy to prevent
this.

Also update chromeos::PowerManagerClientTest to expect this
call.

BUG=646912

Review-Url: https://codereview.chromium.org/2340683003
Cr-Commit-Position: refs/heads/master@{#418864}