[Mac] Don't crash when selecting closed window from Dock menu.

chrome/browser/chrome_application_mac.mm

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/chrome_application_mac.h"
 
 @implementation CrApplication
 
 // -terminate: is the entry point for orderly "quit" operations in Cocoa.
 // This includes the application menu's quit menu item and keyboard
@@ skipping 40 matching lines @@
     return;
 
   [[NSNotificationCenter defaultCenter]
       postNotificationName:NSApplicationWillTerminateNotification
                     object:self];
 
   // Return, don't exit.  The application is responsible for exiting on its
   // own.
 }
 
+- (BOOL)sendAction:(SEL)anAction to:(id)aTarget from:(id)sender {
+  // The Dock menu contains an automagic section where you can select
+  // amongst open windows.  If a window is closed via JavaScript while
+  // the menu is up, the menu item for that window continues to exist.
+  // When a window is selected this method is called with the
+  // now-freed window as |aTarget|.  Short-circuit the call if
+  // |aTarget| is not a valid window.
+  if (anAction == @selector(_selectWindow:)) {
+    // Not using -[NSArray containsObject:] because |aTarget| may be a
+    // freed object.
+    BOOL found = NO;
+    for (NSWindow* window in [self windows]) {
+      if (window == aTarget) {
+        found = YES;
+        break;
+      }
+    }
+    if (!found) {
+      return NO;
+    }
+  }
+
+  return [super sendAction:anAction to:aTarget from:sender];
+}
+
 @end