Add setHandlingEvent method the headless_application for 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
index c69b153d895a5439501701a3e2643769703efb05..b9bdf913919462bc9389c8cad99b8ffd4f55bd34 100644
--- a/headless/lib/browser/headless_shell_application_mac.h
+++ b/headless/lib/browser/headless_shell_application_mac.h
@@ -10,11 +10,15 @@
 
 // Headless shell uses |MessagePumpMac|, so it needs to implement the
 // |CRAppProtocol|.
-@interface HeadlessShellCrApplication : NSApplication<CrAppProtocol>
+@interface HeadlessShellCrApplication
+    : NSApplication<CrAppProtocol, CrAppControlProtocol>
 
 // CrAppProtocol:
 - (BOOL)isHandlingSendEvent;
 
+// CrAppControlProtocol:
+- (void)setHandlingSendEvent:(BOOL)handlingSendEvent;
+
 @end
 
 #endif  // HEADLESS_LIB_BROWSER_HEADLESS_SHELL_APPLICATION_MAC_H_