Update references to the extension messaging APIs to point to the "runtime"

chrome/test/data/extensions/api_test/debugger/background.js

Index: chrome/test/data/extensions/api_test/debugger/background.js
diff --git a/chrome/test/data/extensions/api_test/debugger/background.js b/chrome/test/data/extensions/api_test/debugger/background.js
index 21ff1b5b972bbad2341e8111db2477ac300cb018..0ca46c96a3bb130dba39384b31f4233213b97be4 100644
--- a/chrome/test/data/extensions/api_test/debugger/background.js
+++ b/chrome/test/data/extensions/api_test/debugger/background.js
@@ -48,8 +48,8 @@ chrome.test.runTests([
 
   function sendCommand() {
     function onResponse() {
-      if (chrome.extension.lastError &&
-          chrome.extension.lastError.message.indexOf("invalidMethod") != -1)
+      if (chrome.runtime.lastError &&
+          chrome.runtime.lastError.message.indexOf("invalidMethod") != -1)
         chrome.test.succeed();
       else
         chrome.test.fail();