Move xplat/sonar/xplat/Sonar* to Flipper*

Summary:
Part of the Sonar -> Flipper rename
Intentionally left externally visible buck target as Sonar for now to minimize diff size.

Reviewed By: passy

Differential Revision: D9871684

fbshipit-source-id: 6926eb62c578a05cd895745c75ed7da3cfe965b5

xplat/Flipper/FlipperResponder.h

@@ -0,0 +1,36 @@
+/*
+ *  Copyright (c) 2018-present, Facebook, Inc.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+
+#pragma once
+
+#include <folly/json.h>
+
+namespace facebook {
+namespace flipper {
+
+/**
+ * FlipperResponder is used to asynchronously respond to messages
+ * received from the Sonar desktop app.
+ */
+class FlipperResponder {
+ public:
+  virtual ~FlipperResponder(){};
+
+  /**
+   * Deliver a successful response to the Sonar desktop app.
+   */
+  virtual void success(const folly::dynamic& response) const = 0;
+
+  /**
+   * Inform the Sonar desktop app of an error in handling the request.
+   */
+  virtual void error(const folly::dynamic& response) const = 0;
+};
+
+} // namespace sonar
+} // namespace facebook