API declarations for Call Handover.

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

Bug: 65415068
Test: manual.
Change-Id: I0c2f561d92ad6504f858eadde09980fc1ce8727f
diff --git a/telecomm/java/android/telecom/InCallAdapter.java b/telecomm/java/android/telecom/InCallAdapter.java
index 9bf0467..4bc2a9b 100644
--- a/telecomm/java/android/telecom/InCallAdapter.java
+++ b/telecomm/java/android/telecom/InCallAdapter.java
@@ -435,4 +435,21 @@
         } catch (RemoteException ignored) {
         }
     }
+
+
+    /**
+     * Initiates a handover of this {@link Call} to the {@link ConnectionService} identified
+     * by destAcct.
+     * @param callId The callId of the Call which calls this function.
+     * @param destAcct ConnectionService to which the call should be handed over.
+     * @param videoState The video state desired after the handover.
+     * @param extras Extra information to be passed to ConnectionService
+     */
+    public void handoverTo(String callId, PhoneAccountHandle destAcct, int videoState,
+                           Bundle extras) {
+        try {
+            mAdapter.handoverTo(callId, destAcct, videoState, extras);
+        } catch (RemoteException ignored) {
+        }
+    }
 }