Make sure that we're restoring focus to a valid subview. (with Rohit)...

chrome/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 2006-2008 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.
 
 #include "chrome/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include "base/histogram.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/browser_trial.h"
 #include "chrome/browser/renderer_host/backing_store.h"
@@ skipping 437 matching lines @@
 
 - (BOOL)canBecomeKeyView {
   return canBeKeyView_;
 }
 
 - (BOOL)acceptsFirstResponder {
   return canBeKeyView_;
 }
 
 - (BOOL)becomeFirstResponder {
+  if (![self superview]) {

[pink (ping after 24hrs), 2009/05/28 12:35:23]

I usually check [self window] when determining if I'm in the view hierarchy or
not, since you could have a parent (maybe a NSScrollView or something) but still
be dying. We know a little better in this case, but it still pays to be safe in
case our hierarchy changes, no?

+    // We're dead, so becoming first responder is probably a bad idea.
+    return NO;
+  }
+  
   renderWidgetHostView_->render_widget_host_->Focus();
-
   return YES;
 }
 
 - (BOOL)resignFirstResponder {
   if (closeOnDeactivate_)
     renderWidgetHostView_->KillSelf();
 
   renderWidgetHostView_->render_widget_host_->Blur();
 
   return YES;
 }
 
 @end