[Mac] Fix profile getting re-created / IO allowed dcheck with profile menu.

chrome/browser/ui/cocoa/profile_menu_controller.mm

 // Copyright (c) 2012 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/ui/cocoa/profile_menu_controller.h"
 
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/avatar_menu_model.h"
 #include "chrome/browser/profiles/avatar_menu_model_observer.h"
@@ skipping 157 matching lines @@
 
   [self rebuildMenu];
 }
 
 // Notifies the controller that the active browser has changed and that the
 // menu item and menu need to be updated to reflect that.
 - (void)activeBrowserChangedTo:(Browser*)browser {
   // Tell the model that the browser has changed.
   model_->set_browser(browser);
 
+  // If |browser| is NULL, it may be because the current profile was deleted
+  // and there are no other loaded profiles. In this case, calling
+  // |model_->GetActiveProfileIndex()| may result in a profile being loaded,
+  // which is inappropriate to do on the UI thread.
+  //
+  // An early return provides the desired behavior:
+  //   a) If the profile was deleted, the menu would have been rebuilt and no
+  //      profile will have a check mark.
+  //   b) If the profile was not deleted, but there is no active browser, then
+  //      the previous profile will remain checked.
+  if (!browser)
+    return;
+
   size_t active_profile_index = model_->GetActiveProfileIndex();
 
   // Update the state for the menu items.
   for (size_t i = 0; i < model_->GetNumberOfItems(); ++i) {
     size_t tag = model_->GetItemAt(i).model_index;
     [[[self menu] itemWithTag:tag]
         setState:active_profile_index == tag ? NSOnState
                                              : NSOffState];
   }
 }
@@ skipping 13 matching lines @@
 }
 
 - (NSMenuItem*)createItemWithTitle:(NSString*)title action:(SEL)sel {
   scoped_nsobject<NSMenuItem> item(
       [[NSMenuItem alloc] initWithTitle:title action:sel keyEquivalent:@""]);
   [item setTarget:self];
   return [item.release() autorelease];
 }
 
 @end