[Mac] During shutdown, do not post NSApplicationWillTerminateNotification twice.

chrome/browser/chrome_browser_application_mac.mm

Index: chrome/browser/chrome_browser_application_mac.mm
diff --git a/chrome/browser/chrome_browser_application_mac.mm b/chrome/browser/chrome_browser_application_mac.mm
index 0e151e0bb7dd461b8efa90f95fa91b1981ae7d87..93ea7b0d87902bcda35948c84f836e4219e22b65 100644
--- a/chrome/browser/chrome_browser_application_mac.mm
+++ b/chrome/browser/chrome_browser_application_mac.mm
@@ -331,14 +331,15 @@ void SwizzleInit() {
 // Termination is cancelled by resetting this flag. The standard
 // |-applicationShouldTerminate:| is not supported, and code paths leading to it
 // must be redirected.
+//
+// When the last browser has been destroyed, the BrowserList calls
+// browser::OnAppExiting(), which is the point of no return. That will cause
+// the NSApplicationWillTerminateNotification to be posted, which ends the
+// NSApplication event loop, so final post- MessageLoop::Run() work is done
+// before exiting.
 - (void)terminate:(id)sender {
   AppController* appController = static_cast<AppController*>([NSApp delegate]);
-  if ([appController tryToTerminateApplication:self]) {
-    [[NSNotificationCenter defaultCenter]
-        postNotificationName:NSApplicationWillTerminateNotification
-                      object:self];
-  }
-
+  [appController tryToTerminateApplication:self];
   // Return, don't exit. The application is responsible for exiting on its own.
 }