Remove views::SingleSplitView as it's presently unused.

chrome/browser/ui/views/frame/browser_view_layout.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_LAYOUT_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_LAYOUT_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 11 matching lines @@
 class TabContentsContainer;
 class TabStrip;
 
 namespace gfx {
 class Point;
 class Size;
 }
 
 namespace views {
 class ClientView;
-class SingleSplitView;
 }
 
 namespace web_modal {
 class WebContentsModalDialogHost;
 }
 
 // The layout manager used in chrome browser.
 class BrowserViewLayout : public views::LayoutManager {
  public:
   BrowserViewLayout();
@@ skipping 118 matching lines @@
   gfx::Rect latest_dialog_bounds_;
 
   // The distance the web contents modal dialog is from the top of the window,
   // in pixels.
   int web_contents_modal_dialog_top_y_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserViewLayout);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_BROWSER_VIEW_LAYOUT_H_