[Cronet] Implement getOutputStream in CronetHttpURLConnection

components/cronet/android/java/src/org/chromium/net/urlconnection/CronetOutputStream.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.net.urlconnection;
+
+import org.chromium.net.UploadDataProvider;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * An abstract class of {@link OutputStream} that concrete implementations must
+ * extend in order to be used in {@link CronetHttpURLConnection}.
+ */
+abstract class CronetOutputStream extends OutputStream implements UploadDataProvider {
+    /**
+     * Tells the underlying implementation that connection has been established.
+     * Used in {@link CronetHttpURLConnection}.
+     */
+    abstract void setConnected() throws IOException;
+
+    /**
+     * Checks whether content received is less than Content-Length.
+     * Used in {@link CronetHttpURLConnection}.
+     */
+    abstract void checkReceivedEnoughContent() throws IOException;
+}