Support WebSocket data chunked transfer

Motivation:
Support fetches data chunk by chunk for use with WebSocket chunked transfers.

Modifications:
Create a WebSocketChunkedInput.java that add to io.netty.handler.codec.http.websocketx package

Result:
The WebSocket transfers/fetches data chunk by chunk.

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketChunkedInput.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2016 The Netty Project
+ *
+ * The Netty Project licenses this file to you 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 io.netty.handler.codec.http.websocketx;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufAllocator;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.stream.ChunkedInput;
+import io.netty.util.internal.ObjectUtil;
+
+/**
+ * A {@link ChunkedInput} that fetches data chunk by chunk for use with WebSocket chunked transfers.
+ * <p>
+ * Each chunk from the input data will be wrapped within a {@link ContinuationWebSocketFrame}.
+ * At the end of the input data, {@link ContinuationWebSocketFrame} with finalFragment will be written.
+ * <p>
+ */
+public final class WebSocketChunkedInput implements ChunkedInput<WebSocketFrame> {
+    private final ChunkedInput<ByteBuf> input;
+    private final int rsv;
+
+    /**
+     * Creates a new instance using the specified input.
+     * @param input {@link ChunkedInput} containing data to write
+     */
+    public WebSocketChunkedInput(ChunkedInput<ByteBuf> input) {
+        this(input, 0);
+    }
+
+    /**
+     * Creates a new instance using the specified input.
+     * @param input {@link ChunkedInput} containing data to write
+     * @param rsv RSV1, RSV2, RSV3 used for extensions
+     *
+     * @throws  NullPointerException if {@code input} is null
+     */
+    public WebSocketChunkedInput(ChunkedInput<ByteBuf> input, int rsv) {
+        this.input = ObjectUtil.checkNotNull(input, "input");
+        this.rsv = rsv;
+    }
+
+    /**
+     * @return {@code true} if and only if there is no data left in the stream
+     * and the stream has reached at its end.
+     */
+    @Override
+    public boolean isEndOfInput() throws Exception {
+        return input.isEndOfInput();
+    }
+
+    /**
+     * Releases the resources associated with the input.
+     */
+    @Override
+    public void close() throws Exception {
+        input.close();
+    }
+
+    /**
+     * @deprecated Use {@link #readChunk(ByteBufAllocator)}.
+     *
+     * Fetches a chunked data from the stream. Once this method returns the last chunk
+     * and thus the stream has reached at its end, any subsequent {@link #isEndOfInput()}
+     * call must return {@code true}.
+     *
+     * @param ctx {@link ChannelHandlerContext} context of channelHandler
+     * @return {@link WebSocketFrame} contain chunk of data
+     */
+    @Deprecated
+    @Override
+    public WebSocketFrame readChunk(ChannelHandlerContext ctx) throws Exception {
+        return readChunk(ctx.alloc());
+    }
+
+    /**
+     * Fetches a chunked data from the stream. Once this method returns the last chunk
+     * and thus the stream has reached at its end, any subsequent {@link #isEndOfInput()}
+     * call must return {@code true}.
+     *
+     * @param allocator {@link ByteBufAllocator}
+     * @return {@link WebSocketFrame} contain chunk of data
+     */
+    @Override
+    public WebSocketFrame readChunk(ByteBufAllocator allocator) throws Exception {
+        ByteBuf buf = input.readChunk(allocator);
+        if (buf == null) {
+            return null;
+        }
+        return new ContinuationWebSocketFrame(input.isEndOfInput(), rsv, buf);
+    }
+
+    @Override
+    public long length() {
+        return input.length();
+    }
+
+    @Override
+    public long progress() {
+        return input.progress();
+    }
+}