Add onResponseFailure handler to MetricsHttpChannelListener

service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsHttpChannelListener.java

@@ -105,6 +105,17 @@ public class MetricsHttpChannelListener implements HttpChannel.Listener, Contain
         requestInfo.statusCode(), failure);
   }
 
+  @Override
+  public void onResponseFailure(Request request, Throwable failure) {
+    final RequestInfo requestInfo = getRequestInfo(request);
+
+    logger.warn("Response failure: {} {} ({}) [{}] ",
+        requestInfo.method(),
+        requestInfo.path(),
+        requestInfo.userAgent(),
+        requestInfo.statusCode(), failure);
+  }
+
   @Override
   public void onComplete(final Request request) {