Change the first parameter of savePage.saveAsMHTML to be a dictionary.

chrome/test/data/extensions/api_test/save_page/test.js

Index: chrome/test/data/extensions/api_test/save_page/test.js
diff --git a/chrome/test/data/extensions/api_test/save_page/test.js b/chrome/test/data/extensions/api_test/save_page/test.js
index 9b69cd9aaf19a579f6e388614f9836c546c4ead0..b570684feea52410c6ef6672f4d7c45c25f47d21 100644
--- a/chrome/test/data/extensions/api_test/save_page/test.js
+++ b/chrome/test/data/extensions/api_test/save_page/test.js
@@ -29,7 +29,8 @@ chrome.test.getConfig(function(config) {
       chrome.tabs.getSelected(null, function(tab) {
         chrome.tabs.update(null, { "url": testUrl });
         waitForCurrentTabLoaded(function() {
-          chrome.experimental.savePage.saveAsMHTML(tab.id, function(data) {
+          chrome.experimental.savePage.saveAsMHTML({ "tabId": tab.id },
+              function(data) {
             assertEq(undefined, chrome.extension.lastError);
             assertTrue(data != null);
             // It should contain few KBs of data.