background.js

var utils = {};
utils.ab2t = function (buffer) {
	var arr = new Int8Array(buffer);
	var str = "";
	for(var i = 0, l = arr.length; i < l; i++) {
		str += String.fromCharCode.call(this, arr[i]);
	}
	return str;
};
utils.t2ab = function (str) {
	var buffer = new ArrayBuffer(str.length);
	var view = new DataView(buffer);
	for(var i = 0, l = str.length; i < l; i++) {
		view.setInt8(i, str.charAt(i).charCodeAt());
	}
	return buffer;
};

var proxySocket;
function socketeCreate () {
	chrome.socket.create('tcp', function (info) {
		proxySocket = info.socketId;
		chrome.socket.listen(proxySocket, '0.0.0.0', 24888, 200, function () {
			socketAccept();
		});
	});
}
function socketAccept () {
	chrome.socket.accept(proxySocket, function (info) {
		if (!info.socketId) {
			return;
		}
		var socket = {
			'browser' : info.socketId
		};
		socketAccept();
		browserSetNoDelay(socket);
	});
}
function browserSetNoDelay (socket) {
	chrome.socket.setNoDelay(socket['browser'], true, function () {
		connection(socket);
	});
}
function connection (socket) {
	if (!socket['browser']) {
		return;
	}
	chrome.socket.read(socket['browser'], function (evn) {
		var request = {};
		request['header'] = utils.ab2t(evn.data);
		if (!request['header']) {
			chrome.socket.disconnect(socket['browser']);
			chrome.socket.destroy(socket['browser']);
			return;
		}
		var match = request['header'].match(/Host:\s*(.+?)\r?\n/i);
		if (!match) {
			match = request['header'].match(/GET\s+(.+?)\s/i);
			return;
		}
		request['host'] = match[1];
		chrome.socket.create('tcp', function (info) {
			socket['server'] = info.socketId;
			connectionServer(socket, request);
		});
	});
}
function connectionServer (socket, request) {
	chrome.socket.connect(socket['server'], request['host'], 80, function () {
		chrome.socket.write(socket['server'], utils.t2ab(request['header']), function () {
			readServer(socket, request, {
				'text' : ''
			});
		});
	});
}
function readServer (socket, request, response) {
	chrome.socket.read(socket['server'], function (evn) {
		if (evn.data.byteLength) {
			response['text'] += utils.ab2t(evn.data);
			readServer(socket, request, response);
			return;
		}
		writeBrowser(socket, request, response);
	});
}
function writeBrowser (socket, request, response) {
	chrome.socket.disconnect(socket['server']);
	chrome.socket.destroy(socket['server']);
	delete socket['server'];
	chrome.socket.write(socket['browser'], utils.t2ab(response.text), function () {
		chrome.socket.disconnect(socket['browser']);
		chrome.socket.destroy(socket['browser']);
		delete socket['browser']
	});
}
socketeCreate();

manifest.json

{
  "name": "localproxy for chrome apps",
	"version": "1",
	"manifest_version": 2,
	"minimum_chrome_version": "23",
	"icons": {
		"16": "/src/img/logo.png",
		"128": "/src/img/logo.png"
	},
	"app": {
		"background": {
			"scripts": [
				"/src/js/background.js"
			]
		}
	},
	"permissions": [
		"experimental",
		"http://*/",
		{"socket": ["tcp-listen", "tcp-connect"]}
	]
}