Check for null during notification hangup Intent receipt.

bug:10863336
Change-Id: I775f1855d07cc4f6591ceb51a0f90754ecc833ad
diff --git a/InCallUI/src/com/android/incallui/InCallPresenter.java b/InCallUI/src/com/android/incallui/InCallPresenter.java
index 02ac0be..499dea0 100644
--- a/InCallUI/src/com/android/incallui/InCallPresenter.java
+++ b/InCallUI/src/com/android/incallui/InCallPresenter.java
@@ -308,6 +308,12 @@
      * Hangs up any active or outgoing calls.
      */
     public void hangUpOngoingCall() {
+        // By the time we receive this intent, we could be shut down and call list
+        // could be null.  Bail in those cases.
+        if (mCallList == null) {
+            return;
+        }
+
         Call call = mCallList.getOutgoingCall();
         if (call == null) {
             call = mCallList.getActiveOrBackgroundCall();