Fixes crash in instant. The crash would occur if a malware was showing

chrome/browser/instant/instant_loader.cc

 // Copyright (c) 2011 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/instant/instant_loader.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 601 matching lines @@
     if (preview_contents_->tab_contents()->GetRenderWidgetHostView()) {
 #if defined(OS_MACOSX)
       preview_contents_->tab_contents()->GetRenderWidgetHostView()->
           SetTakesFocusOnlyOnMouseDown(false);
       registrar_.Remove(
           this,
           NotificationType::RENDER_VIEW_HOST_CHANGED,
           Source<NavigationController>(&preview_contents_->controller()));
 #endif
     }
-    preview_contents_->set_delegate(NULL);
+    preview_contents_->tab_contents()->set_delegate(NULL);
     preview_tab_contents_delegate_->Reset();
     ready_ = false;
   }
   update_bounds_timer_.Stop();
   return preview_contents_.release();
 }
 
 bool InstantLoader::ShouldCommitInstantOnMouseUp() {
   return delegate_->ShouldCommitInstantOnMouseUp();
 }
@@ skipping 163 matching lines @@
       Source<NavigationController>(&preview_contents_->controller()));
 #endif
 
   registrar_.Add(
       this,
       NotificationType::NAV_ENTRY_COMMITTED,
       Source<NavigationController>(&preview_contents_->controller()));
 
   preview_contents_->tab_contents()->ShowContents();
 }