ipc: Make sure that ChannelReader is destroyed correctly.

ChannelReader observes the attachment broker, which it gets from a subclass.
Before the subclass is destroyed, ChannelReader must stop observing the
attachment broker.

BUG=493414

Review URL: https://codereview.chromium.org/1321803003

Cr-Commit-Position: refs/heads/master@{#348421}


CrOS-Libchrome-Original-Commit: 53d919d2be1e9ef8e1b728efcc4f18351235d67f
3 files changed
tree: 852135e1ef7950bf57ea9ee51eae029ef0fafc60
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/