[Mac] Prevent using tab context menu after tab closed.

chrome/browser/cocoa/tab_controller.mm

Index: chrome/browser/cocoa/tab_controller.mm
diff --git a/chrome/browser/cocoa/tab_controller.mm b/chrome/browser/cocoa/tab_controller.mm
index 94de7cfc1a72ee6f571fe8d58bdd72cd9d2ad280..0d05c5c0f0197ceb923de54878084d35c6616cb5 100644
--- a/chrome/browser/cocoa/tab_controller.mm
+++ b/chrome/browser/cocoa/tab_controller.mm
@@ -47,6 +47,17 @@
 }
 
 - (void)dealloc {
+  // Since the tab can be closed from JavaScript it is possible for
+  // |contextMenu_| to remain visible after the tab has closed, or for
+  // |closeButton_| to be tracking the mouse.  Make sure neither sends
+  // us an action after -dealloc.
+  [closeButton_ setTarget:nil];
+  [contextMenu_ setAutoenablesItems:NO];
+  for (NSMenuItem* item in [contextMenu_ itemArray]) {
+    [item setTarget:nil];
+    [item setEnabled:NO];
+  }
+
   [[NSNotificationCenter defaultCenter] removeObserver:self];
   [super dealloc];
 }