Implement Call handover initiation side APIs.

Bug: 65415068
Test: Manual

Design doc:
https://docs.google.com/document/d/1qY3oAzjff_4A1ttYb_CGrE_OwTRmXMG_KGsIuPT1ey8/edit#

Change-Id: I692bb14fba66733154378c2dda525aa85c471a38
Merged-in: I692bb14fba66733154378c2dda525aa85c471a38
diff --git a/telecomm/java/android/telecom/Phone.java b/telecomm/java/android/telecom/Phone.java
index 421b1a4..b5394b9 100644
--- a/telecomm/java/android/telecom/Phone.java
+++ b/telecomm/java/android/telecom/Phone.java
@@ -223,6 +223,13 @@
         }
     }
 
+    final void internalOnHandoverFailed(String callId, int error) {
+        Call call = mCallByTelecomCallId.get(callId);
+        if (call != null) {
+            call.internalOnHandoverFailed(error);
+        }
+    }
+
     /**
      * Called to destroy the phone and cleanup any lingering calls.
      */