DO NOT MERGE Add null check to EmergencyCallbackModeExitDialog activity.

It is possible for the mPhone to be null if the activity is invoked
directly from an intent.  This can cause com.android.phone to crash.
Adding a null check to prevent this.

Test: Manual
Bug: 79995313
Change-Id: I9774164d66ffdd17cf9637b4e4fe1e282b60ed97
Merged-In: If1cae5d41cc21c48d248a018dd393c41fe1e595d
1 file changed