User cannot reject a waiting call after a switch call fails

Add new connection event to indicate switch failure.

Test: Manual - Verify that incoming call can be rejected after switch
call is failed.
Bug: 143918738

Change-Id: Ib38ceb3cb72ce946c071a8ec9748a1c81ca58808
diff --git a/telecomm/java/android/telecom/Connection.java b/telecomm/java/android/telecom/Connection.java
index e2f5d0bb..757030e 100644
--- a/telecomm/java/android/telecom/Connection.java
+++ b/telecomm/java/android/telecom/Connection.java
@@ -614,6 +614,15 @@
     public static final String EVENT_CALL_HOLD_FAILED = "android.telecom.event.CALL_HOLD_FAILED";
 
     /**
+     * Connection event used to inform Telecom when a switch operation on a call has failed.
+     * <p>
+     * Sent via {@link #sendConnectionEvent(String, Bundle)}.  The {@link Bundle} parameter is
+     * expected to be null when this connection event is used.
+     */
+    public static final String EVENT_CALL_SWITCH_FAILED =
+            "android.telecom.event.CALL_SWITCH_FAILED";
+
+    /**
      * Connection event used to inform {@link InCallService}s when the process of merging a
      * Connection into a conference has begun.
      * <p>