Implement externally_connectable! Web pages can now communicate directly with

chrome/test/data/extensions/api_test/messaging/externally_connectable/sites/assertions.js

+// Copyright 2013 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.
+
+window.assertions = (function() {
+
+// Codes for test results. Must match ExternallyConnectableMessagingTest::Result
+// in c/b/extensions/extension_messages_apitest.cc.
+var results = {
+  OK: 0,
+  NAMESPACE_NOT_DEFINED: 1,
+  FUNCTION_NOT_DEFINED: 2,
+  COULD_NOT_ESTABLISH_CONNECTION_ERROR: 3,
+  OTHER_ERROR: 4,
+  INCORRECT_RESPONSE: 5
+};
+
+return {
+  canConnectAndSendMessages: function(extensionId) {
+    if (!chrome.runtime) {
+      reply(results.NAMESPACE_NOT_DEFINED);
+      return;
+    }
+
+    if (!chrome.runtime.sendMessage || !chrome.runtime.connect) {
+      reply(results.FUNCTION_NOT_DEFINED);
+      return;
+    }
+
+    // Make the messages sent vaguely complex, but unambiguously JSON-ifiable.
+    var message = [{'a': {'b': 10}}, 20, 'c\x10\x11'];
+
+    function checkLastError(reply) {
+      if (!chrome.runtime.lastError)
+        return true;
+      var kCouldNotEstablishConnection =
+          'Could not establish connection. Receiving end does not exist.';
+      if (chrome.runtime.lastError.message == kCouldNotEstablishConnection)
+        reply(results.COULD_NOT_ESTABLISH_CONNECTION_ERROR);
+      else
+        reply(results.OTHER_ERROR);
+      return false;
+    }
+
+    function checkResponse(response, reply) {
+      var responseJson = JSON.stringify(response);
+      var messageJson = JSON.stringify(message);
+      if (responseJson == messageJson)
+        return true;
+      console.warn('Expected ' + messageJson + ' got ' + responseJson);
+      reply(results.INCORRECT_RESPONSE);
+      return false;
+    }
+
+    function canSendMessage(reply) {
+      chrome.runtime.sendMessage(extensionId, message, function(response) {
+        if (checkLastError(reply) && checkResponse(response, reply))
+          reply(results.OK);
+      });
+    }
+
+    function canConnectAndSendMessages(reply) {
+      var port = chrome.runtime.connect(extensionId);
+      port.postMessage(message, function() {
+        checkLastError(reply);
+      });
+      port.postMessage(message, function() {
+        checkLastError(reply);
+      });
+      var pendingResponses = 2;
+      port.onMessage.addListener(function(response) {

[Jeffrey Yasskin, 2013/06/08 00:28:09]

Do you need to add this listener before posting your messages, or is JS
synchronous enough that it doesn't matter?

[not at google - send to devlin, 2013/06/08 02:02:33]

JS is defined by its single threadedness.

+        pendingResponses--;
+        if (checkLastError(reply) &&

[Jeffrey Yasskin, 2013/06/08 00:28:09]

If the first response produces a lastError, but the second doesn't, I suspect
this will call reply(results.OK) on the second one, producing a duplicate reply.

[not at google - send to devlin, 2013/06/08 02:02:33]

Done.

+            checkResponse(response, reply) &&
+            pendingResponses == 0) {
+          reply(results.OK);
+        }
+      });
+    }
+
+    var done = domAutomationController.send.bind(domAutomationController);
+    canSendMessage(function(result) {
+      if (result != results.OK)
+        done(result);
+      else
+        canConnectAndSendMessages(done);
+    });
+  },
+
+  isDefined: function(name) {
+    var result = results.OK;
+    if (!chrome.runtime)
+      result = results.NAMESPACE_NOT_DEFINED;
+    else if (!chrome.runtime[name])
+      result = results.FUNCTION_NOT_DEFINED;
+    domAutomationController.send(result);
+  }
+};
+
+}());  // window.assertions