Upgraded to manifest format 2

background.js

@@ -0,0 +1,65 @@
+const GBP_TO_EUR_RATE = 'gbp_to_eur_rate';
+const DATE_LAST_RETRIEVED = 'date_rate_last_retrieved';
+
+function todayAsString() {
+    var todayDate = new Date();
+    return todayDate.getDate() + '/' + todayDate.getMonth() + '/' + todayDate.getFullYear();
+}
+
+/**
+ * Fetch the latest GBP to EUR exchange rate by issuing a GET request to
+ * http://download.finance.yahoo.com
+ *
+ * @param callback Function If the response from fetching url has a
+ *     HTTP status of 200, this function is called with a JSON decoded
+ *     response. Otherwise, this function is called with null.
+ */
+function fetchExchangeRate(callback) {
+    var xhr = new XMLHttpRequest();
+    xhr.onreadystatechange = function(data) {
+        if (xhr.readyState == 4) {
+            if (xhr.status == 200) {
+                console.log('xhr.responseText - ' + xhr.responseText);
+                var rate = parseFloat(xhr.responseText.replace(/[\r\n]/g, ""));
+                console.log('parsed rate - ' + rate);
+                // The amount added to rate below is to account for a
+                // difference between the GBP to EURO rate retrieved from
+                // Yahoo and the one Amazon will use. It's not exact but
+                // reflects an average markup Amazon applies to the open
+                // market rate
+                rate = rate + 0.04;
+                gbpToEurRate = rate;
+                localStorage.setItem(GBP_TO_EUR_RATE, rate.toString());
+                localStorage.setItem(DATE_LAST_RETRIEVED, todayAsString());
+                callback(gbpToEurRate);
+            } else {
+                callback(null);
+            }
+        }
+    }
+
+    var url = 'http://download.finance.yahoo.com/d/quotes.csv?s=GBPEUR=X&f=l1&e=.csv';
+    xhr.open('GET', url, true);
+    xhr.send();
+};
+
+/**
+ * Handles data sent via chrome.extension.sendRequest().
+ * @param request Object Data sent in the request.
+ * @param sender Object Origin of the request.
+ * @param callback Function The method to call when the request completes.
+ */
+function onMessage(message, sender, callback) {
+    if (message == 'fetchExchangeRate') {
+        var gbpToEurRate = localStorage.getItem(GBP_TO_EUR_RATE);
+        var dateRateLastRetrieved = localStorage.getItem(DATE_LAST_RETRIEVED);
+        if (gbpToEurRate == null || dateRateLastRetrieved != todayAsString()) {
+            fetchExchangeRate(callback);
+        } else {
+            callback(gbpToEurRate);
+        }
+    }
+};
+
+// Wire up the listener
+chrome.runtime.onMessage.addListener(onMessage);

contentscript.js

@@ -111,5 +111,5 @@
     }
 
     // Send a message back to the extenstion to retrieve the latest GBP to EUR exchange rate    
-    chrome.extension.sendRequest({'action' : 'fetchExchangeRate'}, updatePageWithIrishPrice);
+    chrome.runtime.sendMessage('fetchExchangeRate', updatePageWithIrishPrice);
 })();

manifest.json

@@ -1,6 +1,7 @@
 {
+  "manifest_version": 2,
   "name": "Amazon Prices for Ireland",
-  "version": "1.7",
+  "version": "1.8",
   "description": "Decorate product pages on amazon.co.uk with the equivalent Irish price. This price will be in euro and include the Irish VAT rate.",
   "icons": {
     "128": "images/logo-128.png",
@@ -10,7 +11,10 @@
   "permissions": [
     "http://download.finance.yahoo.com/*"
   ],
-  "background_page" : "background.html",
+  "background": {
+    "scripts": [ "background.js" ],
+    "persistent": false
+  },
   "content_scripts": [
     {
       "matches": ["http://www.amazon.co.uk/*",