Drop the chrome-remote-interface dependency

This patch drops the chrome-remote-interface dependency and
introduces Connection class which handles all the communication
with remote target.

Closes #3

lib/Browser.js

@@ -14,13 +14,13 @@
  * limitations under the License.
  */
 
-var CDP = require('chrome-remote-interface');
 var http = require('http');
 var path = require('path');
 var removeRecursive = require('rimraf').sync;
 var Page = require('./Page');
 var childProcess = require('child_process');
 var Downloader = require('../utils/ChromiumDownloader');
+var Connection = require('./Connection');
 
 var CHROME_PROFILE_PATH = path.resolve(__dirname, '..', '.dev_profile');
 var browserId = 0;
@@ -63,7 +63,6 @@ class Browser {
             this._chromeArguments.push(...options.args);
         this._terminated = false;
         this._chromeProcess = null;
-        this._tabSymbol = Symbol('Browser.TabSymbol');
     }
 
     /**
@@ -73,10 +72,8 @@ class Browser {
         await this._ensureChromeIsRunning();
         if (!this._chromeProcess || this._terminated)
             throw new Error('ERROR: this chrome instance is not alive any more!');
-        var tab = await CDP.New({port: this._remoteDebuggingPort});
+        var client = await Connection.create(this._remoteDebuggingPort);
-        var client = await CDP({tab: tab, port: this._remoteDebuggingPort});
         var page = await Page.create(this, client);
-        page[this._tabSymbol] = tab;
         return page;
     }
 
@@ -86,10 +83,7 @@ class Browser {
     async closePage(page) {
         if (!this._chromeProcess || this._terminated)
             throw new Error('ERROR: this chrome instance is not running');
-        var tab = page[this._tabSymbol];
+        await page.close();
-        if (!tab)
-            throw new Error('ERROR: page does not belong to this chrome instance');
-        await CDP.Close({id: tab.id, port: this._remoteDebuggingPort});
     }
 
     /**
@@ -97,7 +91,7 @@ class Browser {
      */
     async version() {
         await this._ensureChromeIsRunning();
-        var version = await CDP.Version({port: this._remoteDebuggingPort});
+        var version = await Connection.version(this._remoteDebuggingPort);
         return version.Browser;
     }
 

lib/Connection.js

@@ -0,0 +1,152 @@
+/**
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * 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.
+ */
+
+var EventEmitter = require('events');
+var WebSocket = require('ws');
+var http = require('http');
+const COMMAND_TIMEOUT = 10000;
+
+class Connection extends EventEmitter {
+    /**
+     * @param {number} port
+     * @param {string} pageId
+     * @param {!WebSocket} ws
+     */
+    constructor(port, pageId, ws) {
+        super();
+        this._port = port;
+        this._pageId = pageId;
+        this._lastId = 0;
+        /** @type {!Map<number, {resolve: function(*), reject: function(*), method: string}>}*/
+        this._callbacks = new Map();
+
+        this._ws = ws;
+        this._ws.on('message', this._onMessage.bind(this));
+        this._ws.on('close', this._onClose.bind(this));
+    }
+
+    /**
+     * @param {string} method
+     * @param {(!Object|undefined)} params
+     * @return {!Promise<?Object>}
+     */
+    send(method, params = {}) {
+        var id = ++this._lastId;
+        var message = JSON.stringify({id, method, params});
+        this._ws.send(message);
+        return new Promise((resolve, reject) => {
+            this._callbacks.set(id, {resolve, reject, method});
+        });
+    }
+
+    /**
+     * @param {string} message
+     */
+    _onMessage(message) {
+        var object = JSON.parse(message);
+        if (object.id && this._callbacks.has(object.id)) {
+            var callback = this._callbacks.get(object.id);
+            this._callbacks.delete(object.id);
+            if (object.error)
+                callback.reject(new Error(`Protocol error (${callback.method}): ${object.error.message}`));
+            else
+                callback.resolve(object.result);
+        } else {
+            console.assert(!object.id);
+            this.emit(object.method, object.params);
+        }
+    }
+
+    _onClose() {
+        this._ws.removeAllListeners();
+        this._ws.close();
+    }
+
+    /**
+     * @return {!Promise}
+     */
+    async dispose() {
+        await runJsonCommand(this._port, `close/${this._pageId}`);
+    }
+
+    /**
+     * @param {number} port
+     * @return {!Promise<!Connection>}
+     */
+    static async create(port) {
+        var newTab = await runJsonCommand(port, 'new');
+        var url = newTab.webSocketDebuggerUrl;
+
+        return new Promise((resolve, reject) => {
+            var ws = new WebSocket(url, { perMessageDeflate: false });
+            ws.on('open', () => resolve(new Connection(port, newTab.id, ws)));
+            ws.on('error', reject);
+        });
+    }
+
+    /**
+     * @param {number} port
+     * @return {!Promise<!Object>}
+     */
+    static version(port) {
+        return runJsonCommand(port, 'version');
+    }
+}
+
+/**
+ * @param {number} port
+ * @param {string} command
+ * @return {!Promise<!Object>}
+ */
+function runJsonCommand(port, command) {
+    var request = http.get({
+        hostname: 'localhost',
+        port: port,
+        path: '/json/' + command
+    }, onResponse);
+    request.setTimeout(COMMAND_TIMEOUT, onTimeout);
+    var resolve, reject;
+    return new Promise((res, rej) => { resolve = res; reject = rej; });
+
+    function onResponse(response) {
+        var data = '';
+        response.on('data', chunk => data += chunk);
+        response.on('end', () => {
+            if (response.statusCode !== 200) {
+                reject(new Error(`Protocol JSON API error (${command}), status: ${response.statusCode}`));
+                return;
+            }
+            // In the case of 'close' & 'activate' Chromium returns a string rather than JSON: goo.gl/7v27xD
+            if (data === 'Target is closing' || data === 'Target activated') {
+                resolve({message: data});
+                return;
+            }
+            try {
+              resolve(JSON.parse(data));
+            } catch (e) {
+              reject(e);
+            }
+        });
+    }
+
+    function onTimeout() {
+        request.abort();
+        // Reject on error with code specifically indicating timeout in connection setup.
+        reject(new Error('Timeout waiting for initial Debugger Protocol connection.'));
+    }
+}
+
+module.exports = Connection;

lib/Page.js

@@ -474,7 +474,7 @@ class Page extends EventEmitter {
      * @return {!Promise}
      */
     async close() {
-        return this._browser.closePage(this);
+        await this._client.dispose();
     }
 }
 

package.json

@@ -12,7 +12,6 @@
   "author": "The Chromium Authors",
   "license": "SEE LICENSE IN LICENSE",
   "dependencies": {
-    "chrome-remote-interface": "^0.18.0",
     "extract-zip": "^1.6.5",
     "mime": "^1.3.4",
     "progress": "^2.0.0",