Ensure that sendMessage's callback is called.

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

Index: chrome/test/data/extensions/api_test/messaging/connect_crash/page.js
diff --git a/chrome/test/data/extensions/api_test/messaging/connect_crash/page.js b/chrome/test/data/extensions/api_test/messaging/connect_crash/page.js
index b3fc833ace622b5a95755fe6b82d964d6739d57c..769b87f2263d6f916bd50d73f7efdef9ce2bca16 100644
--- a/chrome/test/data/extensions/api_test/messaging/connect_crash/page.js
+++ b/chrome/test/data/extensions/api_test/messaging/connect_crash/page.js
@@ -15,10 +15,6 @@ chrome.runtime.onMessage.addListener(function(msg, sender, sendResponse) {
   // Keep the callback around to avoid test flakiness due to GC.
   ref = sendResponse;
 
-  // TODO(robwu): Remove the following line once crbug.com/439780 is fixed.
-  // (the response callback is not automatically invoked when the tab crashes).
-  sendResponse();
-
   // Keep the port open - do not send a response.
   return true;
 });