Makes the current page dim out when transitioning to instant preview.

chrome/browser/ui/browser_window.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_BROWSER_WINDOW_H_
 #define CHROME_BROWSER_UI_BROWSER_WINDOW_H_
 #pragma once
 
 #include "chrome/browser/tab_contents/navigation_entry.h"
 #include "chrome/common/content_settings_types.h"
@@ skipping 304 matching lines @@
   virtual void Paste() = 0;
 
   // Switches between available tabstrip display modes.
   virtual void ToggleTabStripMode() = 0;
 
 #if defined(OS_MACOSX)
   // Opens the tabpose view.
   virtual void OpenTabpose() = 0;
 #endif
 
+  // See InstantDelegate for details.
+  virtual void PrepareForInstant() = 0;
+
   // Invoked when instant's tab contents should be shown.
   virtual void ShowInstant(TabContents* preview_contents) = 0;
 
   // Invoked when the instant's tab contents should be hidden.
   virtual void HideInstant() = 0;
 
   // Returns the desired bounds for instant in screen coordinates. Note that if
   // instant isn't currently visible this returns the bounds instant would be
   // placed at.
   virtual gfx::Rect GetInstantBounds() = 0;
@@ skipping 40 matching lines @@
 
   // Returns the ToolbarView.
   virtual ToolbarView* GetToolbarView() const = 0;
 #endif
 
  protected:
   virtual ~BrowserWindowTesting() {}
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_WINDOW_H_