Implement shutdown event for macOS

atom/browser/mac/atom_application.h

@@ -2,8 +2,9 @@
 // Use of this source code is governed by the MIT license that can be
 // found in the LICENSE file.
 
-#import "base/mac/scoped_sending_event.h"
-#import "base/mac/scoped_nsobject.h"
+#include "base/callback.h"
+#include "base/mac/scoped_sending_event.h"
+#include "base/mac/scoped_nsobject.h"
 
 @interface AtomApplication : NSApplication<CrAppProtocol,
                                            CrAppControlProtocol,
@@ -13,10 +14,13 @@
   base::scoped_nsobject<NSUserActivity> currentActivity_;
   NSCondition* handoffLock_;
   BOOL updateReceived_;
+  base::Callback<bool()> shouldShutdown_;
 }
 
 + (AtomApplication*)sharedApplication;
 
+- (void)setShutdownHandler:(base::Callback<bool()>)handler;
+
 // CrAppProtocol:
 - (BOOL)isHandlingSendEvent;
 

atom/browser/mac/atom_application.mm

@@ -29,10 +29,16 @@ inline void dispatch_sync_main(dispatch_block_t block) {
 }
 
 - (void)terminate:(id)sender {
+  if (shouldShutdown_ && !shouldShutdown_.Run())
+    return;  // User will call Quit later.
   AtomApplicationDelegate* atomDelegate = (AtomApplicationDelegate*) [NSApp delegate];
   [atomDelegate tryToTerminateApp:self];
 }
 
+- (void)setShutdownHandler:(base::Callback<bool()>)handler {
+  shouldShutdown_ = std::move(handler);
+}
+
 - (BOOL)isHandlingSendEvent {
   return handlingSendEvent_;
 }