Add browser tests for loading notification icons from blob and data URLs.

chrome/test/data/notifications/platform_notification_service.html

Index: chrome/test/data/notifications/platform_notification_service.html
diff --git a/chrome/test/data/notifications/platform_notification_service.html b/chrome/test/data/notifications/platform_notification_service.html
index 3c6ea37e2ad2376eaa6bcf2984f773bde2b6147d..e257635f26c7c4db0cdb4b0d662cc7c061525ecd 100644
--- a/chrome/test/data/notifications/platform_notification_service.html
+++ b/chrome/test/data/notifications/platform_notification_service.html
@@ -58,6 +58,49 @@
         });
       }
 
+      // Helper function to request icon.png, returns a promise that will be

[johnme, 2015/03/19 12:24:29]

Nit: you could just use fetch

[Peter Beverloo, 2015/03/19 12:30:02]

Done.

+      // resolved with the response's content when complete.
+      function RequestResource(url, type) {
+        return new Promise(function(resolve) {
+          var request = new XMLHttpRequest();
+          request.open('GET', url, true);
+          request.responseType = type;
+
+          request.onload = function() {
+            resolve(request.response);
+          };
+
+          request.send();
+        });
+      }
+
+      // Displays a persistent notification with a data: URL as its image.
+      function DisplayPersistentNotificationDataUrlImage() {
+        RequestResource('icon.png', 'arraybuffer').then(function(arrayBuffer) {
+          var uint8Array = new Uint8Array(arrayBuffer),
+              string = new Array(uint8Array.length);
+
+          for (var i = 0; i < uint8Array.length; ++i)
+            string[i] = String.fromCharCode(uint8Array[i]);

[johnme, 2015/03/19 12:24:29]

I'm a little freaked out by the need to convert everything to string characters.
It would probably be neater to use FileReader.readAsDataURL (taking a blob from
fetch): http://stackoverflow.com/a/18650249

[Peter Beverloo, 2015/03/19 12:30:02]

Done.

+
+          var data = string.join('');
+          DisplayPersistentNotification('Data URL Title', {
+            body: 'Contents',
+            icon: 'data:image/png;base64,' + btoa(data)
+          })
+        });
+      }
+
+      // Displays a persistent notification with a blob URL as its image.
+      function DisplayPersistentNotificationBlobImage() {
+        RequestResource('icon.png', 'blob').then(function(blob) {
+          DisplayPersistentNotification('Blob Title', {
+            body: 'Contents',
+            icon: URL.createObjectURL(blob)
+          });
+        });
+      }
+
       // Returns the latest received message from the worker. If no message has
       // been received, nothing will be done. For successfully registered
       // Service Workers this is OK, however, since the "message" event handler