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

chrome/test/data/extensions/browsertest/last_error/bg.js

Index: chrome/test/data/extensions/browsertest/last_error/bg.js
diff --git a/chrome/test/data/extensions/browsertest/last_error/bg.js b/chrome/test/data/extensions/browsertest/last_error/bg.js
index e9f2309e5e76a33860573ddc587d9360fa43a57f..71563d953017bafc3b0d47e0bc0d040af9d1199e 100644
--- a/chrome/test/data/extensions/browsertest/last_error/bg.js
+++ b/chrome/test/data/extensions/browsertest/last_error/bg.js
@@ -36,8 +36,8 @@ function testLastError() {
     // Now ask for the next highest tabId.
     chrome.tabs.get(maxTabId + 1, function(tab) {
       // Make sure lastError *is* set and tab is not.
-      if (!chrome.extension.lastError ||
-          !chrome.extension.lastError.message ||
+      if (!chrome.runtime.lastError ||
+          !chrome.runtime.lastError.message ||
           tab)
         fail();