[Mac] Stop listening for NSWindowWillCloseNotification in |-dealloc| to fix a crash.

chrome/browser/ui/cocoa/browser/avatar_button_controller.mm

Index: chrome/browser/ui/cocoa/browser/avatar_button_controller.mm
diff --git a/chrome/browser/ui/cocoa/browser/avatar_button_controller.mm b/chrome/browser/ui/cocoa/browser/avatar_button_controller.mm
index 39aa4f012c311db88b616e8a84ff31cd77534705..5f306d2fb72bfa41bb960ceba21d92fe77e073be 100644
--- a/chrome/browser/ui/cocoa/browser/avatar_button_controller.mm
+++ b/chrome/browser/ui/cocoa/browser/avatar_button_controller.mm
@@ -132,6 +132,14 @@ const CGFloat kMenuYOffsetAdjust = 1.0;
   return self;
 }
 
+- (void)dealloc {
+  [[NSNotificationCenter defaultCenter]
+      removeObserver:self
+                name:NSWindowWillCloseNotification
+              object:[menuController_ window]];
+  [super dealloc];
+}
+
 - (NSButton*)buttonView {
   return static_cast<NSButton*>(self.view);
 }