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

chrome/common/extensions/docs/examples/api/eventPage/basic/content.js

Index: chrome/common/extensions/docs/examples/api/eventPage/basic/content.js
diff --git a/chrome/common/extensions/docs/examples/api/eventPage/basic/content.js b/chrome/common/extensions/docs/examples/api/eventPage/basic/content.js
index cf9c603376a60a63bbc59b9d46425b6105a76376..3bb880cca51b794f9c268077c2c13b3c988288e8 100644
--- a/chrome/common/extensions/docs/examples/api/eventPage/basic/content.js
+++ b/chrome/common/extensions/docs/examples/api/eventPage/basic/content.js
@@ -22,23 +22,23 @@ addButton("Clear logs", function() {
 });
 
 addButton("Send message with delayed response", function() {
-  chrome.extension.sendMessage({delayedResponse: true}, function(response) {
+  chrome.runtime.sendMessage({delayedResponse: true}, function(response) {
     log("Background page responded: " + response);
   });
 });
 
 addButton("Show counters", function() {
-  chrome.extension.sendMessage({getCounters: true}, function(response) {
+  chrome.runtime.sendMessage({getCounters: true}, function(response) {
     log("In-memory counter is: " + response.counter);
     log("Persisted counter is: " + response.persistentCounter);
   });
 });
 
 addButton("Set an alarm", function() {
-  chrome.extension.sendMessage({setAlarm: true});
+  chrome.runtime.sendMessage({setAlarm: true});
 });
 
-chrome.extension.onMessage.addListener(function(msg, _, sendResponse) {
+chrome.runtime.onMessage.addListener(function(msg, _, sendResponse) {
   log("Got message from background page: " + msg);
 });