Add plumbing for merge failures and renable button. (3/4)

The merge failure is not plumbed up through any layer that
can trap the callback and act on it.  The first part of this
fix is to create that plumbing.  Then we need to reenable the
merge button. At this point in time, we leverage the fact
that forcing the call to reassess its capabilities will poke
the InCallUI to reenable the merge button. In the future, we
should plumb the merge failure all the way to InCallUI and
not only handle the button but display UI to the user. The UI
is currently being displayed by CallNotifier which is the wrong
place. See b/20530631 for more details.

Bug: 20229905
Change-Id: I0355ada46b484c6db4bee656c77386dd61be5e1f
diff --git a/telecomm/java/android/telecom/ConnectionServiceAdapter.java b/telecomm/java/android/telecom/ConnectionServiceAdapter.java
index d026a28..a87dbe7 100644
--- a/telecomm/java/android/telecom/ConnectionServiceAdapter.java
+++ b/telecomm/java/android/telecom/ConnectionServiceAdapter.java
@@ -203,6 +203,21 @@
     }
 
     /**
+     * Indicates that the merge request on this call has failed.
+     *
+     * @param callId The unique ID of the call being conferenced.
+     */
+    void onConferenceMergeFailed(String callId) {
+        for (IConnectionServiceAdapter adapter : mAdapters) {
+            try {
+                Log.d(this, "merge failed for call %s", callId);
+                adapter.setConferenceMergeFailed(callId);
+            } catch (RemoteException ignored) {
+            }
+        }
+    }
+
+    /**
      * Indicates that the call no longer exists. Can be used with either a call or a conference
      * call.
      *