Merge changes Iee4e3db8,I6e74c7fe,Ibe722477,Ia22751f0,Ic28fb197, ...

* changes:
  DialpadView cleanup.
  Merge the following methods in InCallActivityCommon into InCallActivity:
  Add contact source options.
  Automated rollback of changelist 174944384
  Refactoring and adding TOS check before transcribing
  Adding exponential backoff utilities
  Implement suggested SIM
  Fix dialer simulator for conference calling funcitonality. Updated the following contents: 1.Fix the order of spawning connections for GSM conference. 2.Make VOLTE conference call more realistic. 3.Fix minor bugs about simulator. 4.Add SimulatorConnectionsBank class to store connection tags created by simulator. 5.Fix tests influenced by SimulatorConnectionsBank.