Add frameId to MessageSender (extension messaging API)

chrome/test/data/extensions/api_test/messaging/connect/page.js

Index: chrome/test/data/extensions/api_test/messaging/connect/page.js
diff --git a/chrome/test/data/extensions/api_test/messaging/connect/page.js b/chrome/test/data/extensions/api_test/messaging/connect/page.js
index 1e3a7e8eb3dcc68b0c9b3f2f7ba8204ef1819a7a..d784f9caf1ac6faf1c3d9ea9edc02249fbeccfa3 100644
--- a/chrome/test/data/extensions/api_test/messaging/connect/page.js
+++ b/chrome/test/data/extensions/api_test/messaging/connect/page.js
@@ -29,6 +29,8 @@ chrome.runtime.onConnect.addListener(function(port) {
       testPostMessageFromTab(port);
     } else if (msg.testSendMessageFromTab) {
       testSendMessageFromTab();
+    } else if (msg.testSendMessageFromFrame) {
+      testSendMessageFromFrame();
     } else if (msg.testDisconnect) {
       port.disconnect();
     } else if (msg.testDisconnectOnClose) {
@@ -65,6 +67,14 @@ function testSendMessageFromTab() {
   });
 }
 
+function testSendMessageFromFrame() {
+  var f = document.createElement('iframe');
+  f.src = '?frame_test';
+  document.body.appendChild(f);

[not at google - send to devlin, 2014/11/11 00:03:04]

Ideally you'd test with more than 1 frame.

[robwu, 2014/11/11 00:34:26]

Done.

+  // The test will continue in frame.js (a content script that runs at
+  // ?frame_test, declared in manifest.json).

[not at google - send to devlin, 2014/11/11 00:03:04]

A more useful comment would explain what the frame_test parameter is actually
used for; it's so that the content script matches the frame or something? Using
tabs.executeScript would be a nicer way to do that, though I suppose it's a bit
harder to get working due to race conditions.

In either case: while the arbitrarily named "frame_test" is ok, it might be nice
to name it after the test which is using it, so "testSendMessageFromFrame".

[robwu, 2014/11/11 00:34:26]

Done.

+}
+
 // Tests sendMessage to an invalid extension.
 function testSendMessageFromTabError() {
   // try sending a request to a bad extension id