buffet: Add support for DEVICE_DELETED XMPP notification

When DEVICE_DELETED notification is received over XMPP channel,
buffet will remove any cloud registration information (credentials,
robot account) and close server connections (XMPP channel, etc).

BUG=brillo:1215
TEST=`FEATURES=test emerge-link buffet`
     Test manually on the device.

Change-Id: I86e19659b9fbc06685bcabb6c659a633e797cae5
Reviewed-on: https://chromium-review.googlesource.com/281666
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/notification/notification_parser.cc b/buffet/notification/notification_parser.cc
index 5885afa..8cde3fa 100644
--- a/buffet/notification/notification_parser.cc
+++ b/buffet/notification/notification_parser.cc
@@ -23,6 +23,19 @@
   return true;
 }
 
+// Processes DEVICE_DELETED notifications.
+bool ParseDeviceDeleted(const base::DictionaryValue& notification,
+                        NotificationDelegate* delegate) {
+  std::string device_id;
+  if (!notification.GetString("deviceId", &device_id)) {
+    LOG(ERROR) << "DEVICE_DELETED notification is missing 'deviceId' property";
+    return false;
+  }
+
+  delegate->OnDeviceDeleted(device_id);
+  return true;
+}
+
 }  // anonymous namespace
 
 bool ParseNotificationJson(const base::DictionaryValue& notification,
@@ -46,6 +59,9 @@
   if (type == "COMMAND_CREATED")
     return ParseCommandCreated(notification, delegate);
 
+  if (type == "DEVICE_DELETED")
+    return ParseDeviceDeleted(notification, delegate);
+
   // Here we ignore other types of notifications for now.
   LOG(INFO) << "Ignoring push notification of type " << type;
   return true;