Added missing interface file.

Author: Noor Dawod

library/src/main/java/com/loopj/android/http/PreProcessingInterface.java

@@ -0,0 +1,49 @@
+/*
+    Android Asynchronous Http Client
+    Copyright (c) 2011 James Smith <[email protected]>
+    http://loopj.com
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+package com.loopj.android.http;
+
+import org.apache.http.HttpRequest;
+import org.apache.http.HttpResponse;
+
+/**
+ * This interface is used to define pre- and post-processing handlers for every
+ * request, and response, passing through the library.
+ *
+ * @author Noor Dawod <[email protected]>
+ */
+public interface PreProcessingInterface {
+
+    /**
+     * This method is called right before the passed request is processed by
+     * the executor service. This is only called once regardless if the request is
+     * successful or not.
+     *
+     * @param request The request that's about to be processed by the executor
+     */
+    void onPreProcessRequest(final HttpRequest request);
+
+    /**
+     * This method is called right before {@link ResponseHandlerInterface} methods
+     * are called in order to process success or failure requests. This is only
+     * called once for processing.
+     *
+     * @param response The response that's about to be processed by {@link ResponseHandlerInterface} handler
+     */
+    void onPreProcessResponse(final HttpResponse response);
+}