Add browser test for notification action icons.

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 fa754adde820d9e6ce5835cd686af08becd3ed9b..6d46e15800da137165f59cea2cc805594c13bfa1 100644
--- a/chrome/test/data/notifications/platform_notification_service.html
+++ b/chrome/test/data/notifications/platform_notification_service.html
@@ -60,6 +60,9 @@
           requireInteraction: true,
           data: [
             { property: 'value' }
+          ],
+          actions: [
+            { action: 'actionId', title: 'actionTitle', icon: 'icon.png' }
           ]
         });
       }
@@ -100,6 +103,17 @@
         });
       }
 
+      // Displays a persistent notification with action buttons.
+      function DisplayPersistentNotificationWithActionButtons() {
+        DisplayPersistentNotification('action_button_click', {
+          body: 'Contents',
+          actions: [
+            { action: 'actionId1', title: 'actionTitle1', icon: 'icon.png' },
+            { action: 'actionId2', title: 'actionTitle2', icon: 'icon.png' }
+          ]
+        });
+      }
+
       // 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