Add CrAppProtocol for headless on Mac

headless/lib/browser/headless_shell_application_mac.h

Index: headless/lib/browser/headless_shell_application_mac.h
diff --git a/headless/lib/browser/headless_shell_application_mac.h b/headless/lib/browser/headless_shell_application_mac.h
new file mode 100644
index 0000000000000000000000000000000000000000..c69b153d895a5439501701a3e2643769703efb05
--- /dev/null
+++ b/headless/lib/browser/headless_shell_application_mac.h
@@ -0,0 +1,20 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef HEADLESS_LIB_BROWSER_HEADLESS_SHELL_APPLICATION_MAC_H_
+#define HEADLESS_LIB_BROWSER_HEADLESS_SHELL_APPLICATION_MAC_H_
+
+#include "base/mac/scoped_sending_event.h"
+#include "base/message_loop/message_pump_mac.h"
+
+// Headless shell uses |MessagePumpMac|, so it needs to implement the
+// |CRAppProtocol|.
+@interface HeadlessShellCrApplication : NSApplication<CrAppProtocol>
+
+// CrAppProtocol:
+- (BOOL)isHandlingSendEvent;
+
+@end
+
+#endif  // HEADLESS_LIB_BROWSER_HEADLESS_SHELL_APPLICATION_MAC_H_