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_unittest.cc b/buffet/notification/notification_parser_unittest.cc
index c6be507..d578b55 100644
--- a/buffet/notification/notification_parser_unittest.cc
+++ b/buffet/notification/notification_parser_unittest.cc
@@ -9,6 +9,7 @@
 
 #include "buffet/commands/unittest_utils.h"
 
+using testing::SaveArg;
 using testing::Invoke;
 using testing::_;
 
@@ -22,6 +23,7 @@
   MOCK_METHOD0(OnDisconnected, void());
   MOCK_METHOD0(OnPermanentFailure, void());
   MOCK_METHOD1(OnCommandCreated, void(const base::DictionaryValue& command));
+  MOCK_METHOD1(OnDeviceDeleted, void(const std::string&));
 };
 
 class NotificationParserTest : public ::testing::Test {
@@ -72,6 +74,19 @@
   EXPECT_JSON_EQ(expected_json, command_instance);
 }
 
+TEST_F(NotificationParserTest, DeviceDeleted) {
+  auto json = CreateDictionaryValue(R"({
+    "kind":"clouddevices#notification",
+    "type":"DEVICE_DELETED",
+    "deviceId":"some_device_id"
+  })");
+
+  std::string device_id;
+  EXPECT_CALL(delegate_, OnDeviceDeleted(_)).WillOnce(SaveArg<0>(&device_id));
+  EXPECT_TRUE(ParseNotificationJson(*json, &delegate_));
+  EXPECT_EQ("some_device_id", device_id);
+}
+
 TEST_F(NotificationParserTest, Failure_NoKind) {
   auto json = CreateDictionaryValue(R"({
     "type": "COMMAND_CREATED",