Stops javascript alerts and unload dialogs from showing during

chrome/browser/instant/instant_loader.cc

 // Copyright (c) 2010 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 <utility>
 
 #include "app/l10n_util.h"
@@ skipping 258 matching lines @@
   virtual void UpdateTargetURL(TabContents* source, const GURL& url) {}
   virtual void ContentsMouseEvent(
       TabContents* source, const gfx::Point& location, bool motion) {}
   virtual void ContentsZoomChange(bool zoom_in) {}
   virtual void OnContentSettingsChange(TabContents* source) {}
   virtual bool IsApplication() const { return false; }
   virtual void ConvertContentsToApplication(TabContents* source) {}
   virtual bool CanReloadContents(TabContents* source) const { return true; }
   virtual void ShowHtmlDialog(HtmlDialogUIDelegate* delegate,
                               gfx::NativeWindow parent_window) {}
+  virtual bool ShouldSuppressDialogs() {
+    // Any message shown during instant cancels instant, so we suppress them.
+    return true;
+  }
   virtual void BeforeUnloadFired(TabContents* tab,
                                  bool proceed,
                                  bool* proceed_to_fire_unload) {}
   virtual void ForwardMessageToExternalHost(const std::string& message,
                                             const std::string& origin,
                                             const std::string& target) {}
   virtual bool IsExternalTabContainer() const { return false; }
   virtual void SetFocusToLocationBar(bool select_all) {}
   virtual bool ShouldFocusPageAfterCrash() { return false; }
   virtual void RenderWidgetShowing() {}
@@ skipping 489 matching lines @@
         SetTakesFocusOnlyOnMouseDown(true);
   }
   registrar_.Add(
       this,
       NotificationType::RENDER_VIEW_HOST_CHANGED,
       Source<NavigationController>(&preview_contents_->controller()));
 #endif
 
   preview_contents_->tab_contents()->ShowContents();
 }