1 files changed, 352 insertions, 0 deletions
diff --git a/chromium/chrome/browser/resources/chromeos/chromevox/host/chrome/extension_bridge.js b/chromium/chrome/browser/resources/chromeos/chromevox/host/chrome/extension_bridge.js
new file mode 100644
index 00000000000..722c7e0b150
--- /dev/null
+++ b/chromium/chrome/browser/resources/chromeos/chromevox/host/chrome/extension_bridge.js
@@ -0,0 +1,352 @@
+// Copyright 2014 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.
+
+/**
+ * @fileoverview Bridge to aid in communication between a Chrome
+ * background page and content script.
+ *
+ * It automatically figures out where it's being run and initializes itself
+ * appropriately. Then just call send() to send a message from the background
+ * to the page or vice versa, and addMessageListener() to provide a message
+ * listener.  Messages can be any object that can be serialized using JSON.
+ *
+ */
+
+goog.provide('cvox.ExtensionBridge');
+
+goog.require('cvox.ChromeVoxJSON');
+
+/**
+ * @constructor
+ */
+cvox.ExtensionBridge = function() {};
+
+/**
+ * Initialize the extension bridge. Dynamically figure out whether we're in
+ * the background page, content script, or in a page, and call the
+ * corresponding function for more specific initialization.
+ */
+cvox.ExtensionBridge.init = function() {
+  var self = cvox.ExtensionBridge;
+  self.messageListeners = [];
+  self.disconnectListeners = [];
+
+  if (/^chrome-extension:\/\/.*background\.html$/.test(window.location.href)) {
+    // This depends on the fact that the background page has a specific url. We
+    // should never be loaded into another extension's background page, so this
+    // is a safe check.
+    self.context = self.BACKGROUND;
+    self.initBackground();
+    return;
+  }
+
+  if (chrome && chrome.extension) {
+    self.context = self.CONTENT_SCRIPT;
+    self.initContentScript();
+  }
+};
+
+/**
+ * Constant indicating we're in a background page.
+ * @type {number}
+ * @const
+ */
+cvox.ExtensionBridge.BACKGROUND = 0;
+
+/**
+ * Constant indicating we're in a content script.
+ * @type {number}
+ * @const
+ */
+cvox.ExtensionBridge.CONTENT_SCRIPT = 1;
+
+/**
+ * The name of the port between the content script and background page.
+ * @type {string}
+ * @const
+ */
+cvox.ExtensionBridge.PORT_NAME = 'cvox.ExtensionBridge.Port';
+
+/**
+ * The name of the message between the content script and background to
+ * see if they're connected.
+ * @type {string}
+ * @const
+ */
+cvox.ExtensionBridge.PING_MSG = 'cvox.ExtensionBridge.Ping';
+
+/**
+ * The name of the message between the background and content script to
+ * confirm that they're connected.
+ * @type {string}
+ * @const
+ */
+cvox.ExtensionBridge.PONG_MSG = 'cvox.ExtensionBridge.Pong';
+
+/**
+ * Send a message. If the context is a page, sends a message to the
+ * extension background page. If the context is a background page, sends
+ * a message to the current active tab (not all tabs).
+ *
+ * @param {Object} message The message to be sent.
+ */
+cvox.ExtensionBridge.send = function(message) {
+  var self = cvox.ExtensionBridge;
+  switch (self.context) {
+  case self.BACKGROUND:
+    self.sendBackgroundToContentScript(message);
+    break;
+  case self.CONTENT_SCRIPT:
+    self.sendContentScriptToBackground(message);
+    break;
+  }
+};
+
+/**
+ * Provide a function to listen to messages. In page context, this
+ * listens to messages from the background. In background context,
+ * this listens to messages from all pages.
+ *
+ * The function gets called with two parameters: the message, and a
+ * port that can be used to send replies.
+ *
+ * @param {function(Object, Port)} listener The message listener.
+ */
+cvox.ExtensionBridge.addMessageListener = function(listener) {
+  cvox.ExtensionBridge.messageListeners.push(listener);
+};
+
+/**
+ * Provide a function to be called when the connection is
+ * disconnected.
+ *
+ * @param {function()} listener The listener.
+ */
+cvox.ExtensionBridge.addDisconnectListener = function(listener) {
+  cvox.ExtensionBridge.disconnectListeners.push(listener);
+};
+
+/**
+ * Removes all message listeners from the extension bridge.
+ */
+cvox.ExtensionBridge.removeMessageListeners = function() {
+  cvox.ExtensionBridge.messageListeners.length = 0;
+};
+
+/**
+ * Returns a unique id for this instance of the script.
+ *
+ * @return {number}
+ */
+cvox.ExtensionBridge.uniqueId = function() {
+  return cvox.ExtensionBridge.id_;
+};
+
+/**
+ * Initialize the extension bridge in a background page context by registering
+ * a listener for connections from the content script.
+ */
+cvox.ExtensionBridge.initBackground = function() {
+  var self = cvox.ExtensionBridge;
+
+  /** @type {!Array.<Port>} @private */
+  self.portCache_ = [];
+  /** @type {number} */
+  self.nextPongId_ = 1;
+  /** @type {number} */
+  self.id_ = 0;
+
+  var onConnectHandler = function(port) {
+    if (port.name != self.PORT_NAME) {
+      return;
+    }
+
+    self.portCache_.push(port);
+
+    port.onMessage.addListener(
+        function(message) {
+          if (message[cvox.ExtensionBridge.PING_MSG]) {
+            var pongMessage = {};
+            pongMessage[cvox.ExtensionBridge.PONG_MSG] = self.nextPongId_++;
+            port.postMessage(pongMessage);
+	    return;
+	  }
+          for (var i = 0; i < self.messageListeners.length; i++) {
+            self.messageListeners[i](message, port);
+          }
+        });
+
+    port.onDisconnect.addListener(function(message) {
+      for (var i = 0; i < self.portCache_.length; i++) {
+        if (self.portCache_[i] == port) {
+          self.portCache_.splice(i, 1);
+          break;
+        }
+      }
+    });
+  };
+
+  chrome.extension.onConnect.addListener(onConnectHandler);
+};
+
+/**
+ * Initialize the extension bridge in a content script context, listening
+ * for messages from the background page.
+ */
+cvox.ExtensionBridge.initContentScript = function() {
+  var self = cvox.ExtensionBridge;
+  self.connected = false;
+  self.pingAttempts = 0;
+  self.queuedMessages = [];
+  /** @type {number} */
+  self.id_ = -1;
+
+  var onMessageHandler = function(request, sender, sendResponse) {
+    if (request && request['srcFile']) {
+      // TODO (clchen, deboer): Investigate this further and come up with a
+      // cleaner solution. The root issue is that this should never be run on
+      // the background page, but it is in the Chrome OS case.
+      return;
+    }
+    if (request[cvox.ExtensionBridge.PONG_MSG]) {
+      self.gotPongFromBackgroundPage(request[cvox.ExtensionBridge.PONG_MSG]);
+    } else {
+      for (var i = 0; i < self.messageListeners.length; i++) {
+        self.messageListeners[i](request, cvox.ExtensionBridge.backgroundPort);
+      }
+    }
+    sendResponse({});
+  };
+
+  // Listen to requests from the background that don't come from
+  // our connection port.
+  chrome.extension.onMessage.addListener(onMessageHandler);
+
+  self.setupBackgroundPort();
+
+  self.tryToPingBackgroundPage();
+};
+
+/**
+ * Set up the connection to the background page.
+ */
+cvox.ExtensionBridge.setupBackgroundPort = function() {
+  // Set up the connection to the background page.
+  var self = cvox.ExtensionBridge;
+  self.backgroundPort = chrome.extension.connect({name: self.PORT_NAME});
+  self.backgroundPort.onMessage.addListener(
+      function(message) {
+        if (message[cvox.ExtensionBridge.PONG_MSG]) {
+          self.gotPongFromBackgroundPage(
+              message[cvox.ExtensionBridge.PONG_MSG]);
+        } else {
+          for (var i = 0; i < self.messageListeners.length; i++) {
+            self.messageListeners[i](message, self.backgroundPort);
+          }
+        }
+      });
+  self.backgroundPort.onDisconnect.addListener(
+      function(event) {
+        // If we're not connected yet, don't give up - try again.
+        if (!self.connected) {
+          self.backgroundPort = null;
+	  return;
+	}
+
+        for (var i = 0; i < self.disconnectListeners.length; i++) {
+          self.disconnectListeners[i]();
+        }
+      });
+};
+
+/**
+ * Try to ping the background page.
+ */
+cvox.ExtensionBridge.tryToPingBackgroundPage = function() {
+  var self = cvox.ExtensionBridge;
+
+  // If we already got a pong, great - we're done.
+  if (self.connected) {
+    return;
+  }
+
+  self.pingAttempts++;
+  if (self.pingAttempts > 5) {
+    // Could not connect after 5 ping attempts. Call the disconnect
+    // handlers, which will disable ChromeVox.
+    for (var i = 0; i < self.disconnectListeners.length; i++) {
+      self.disconnectListeners[i]();
+    }
+    return;
+  }
+
+  // Send the ping.
+  var msg = {};
+  msg[cvox.ExtensionBridge.PING_MSG] = 1;
+  if (!self.backgroundPort) {
+    self.setupBackgroundPort();
+  }
+  self.backgroundPort.postMessage(msg);
+
+  // Check again in 500 ms in case we get no response.
+  window.setTimeout(cvox.ExtensionBridge.tryToPingBackgroundPage, 500);
+};
+
+/**
+ * Got pong from the background page, now we know the connection was
+ * successful.
+ * @param {number} pongId unique id assigned to us by the background page
+ */
+cvox.ExtensionBridge.gotPongFromBackgroundPage = function(pongId) {
+  var self = cvox.ExtensionBridge;
+  self.connected = true;
+  self.id_ = pongId;
+
+  while (self.queuedMessages.length > 0) {
+    self.sendContentScriptToBackground(self.queuedMessages.shift());
+  }
+};
+
+/**
+ * Send a message from the content script to the background page.
+ *
+ * @param {Object} message The message to send.
+ */
+cvox.ExtensionBridge.sendContentScriptToBackground = function(message) {
+  var self = cvox.ExtensionBridge;
+  if (!self.connected) {
+    // We're not connected to the background page, so queue this message
+    // until we're connected.
+    self.queuedMessages.push(message);
+    return;
+  }
+
+  if (cvox.ExtensionBridge.backgroundPort) {
+    cvox.ExtensionBridge.backgroundPort.postMessage(message);
+  } else {
+    chrome.extension.sendMessage(message);
+  }
+};
+
+/**
+ * Send a message from the background page to the content script of the
+ * current selected tab.
+ *
+ * @param {Object} message The message to send.
+ */
+cvox.ExtensionBridge.sendBackgroundToContentScript = function(message) {
+  chrome.tabs.query(
+      {'active': true, 'lastFocusedWindow': true},
+      function(tabs) {
+        if (tabs && tabs.length > 0) {
+          chrome.tabs.sendMessage(tabs[0].id, message);
+        } else {
+          cvox.ExtensionBridge.portCache_.forEach(function(port) {
+            port.postMessage(message);
+          });
+        }
+      });
+};
+
+cvox.ExtensionBridge.init();