Bug 1058397 - Part 1: Separate TelephonyCallback. r=hsinyi
Bug 1058397 - Part 2: USSDSession interface. r=hsinyi
Bug 1058397 - Part 3: USSDSession implement. r=hsinyi
Bug 1058397 - Part 4: Wrap system message. r=hsinyi
Bug 1058397 - Part 5: Fix test: USSDReceivedEvent is not exposed. r=bzbarsky