GPU: Only restore one texture unit in ScopedTextureBinder.

ui/gl/gl_state_restorer.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 UI_GL_GL_STATE_RESTORER_H_
 #define UI_GL_GL_STATE_RESTORER_H_
 
 #include "base/basictypes.h"
 #include "ui/gl/gl_export.h"
 
 namespace gfx {
 
 // An interface for Restoring GL State.
 // This will expand over time to provide an more optimizable implementation.
 class GL_EXPORT GLStateRestorer {
  public:
   GLStateRestorer();
   virtual ~GLStateRestorer();
 
   virtual bool IsInitialized() = 0;
   virtual void RestoreState(const GLStateRestorer* prev_state) = 0;
   virtual void RestoreAllTextureUnitBindings() = 0;
+  virtual void RestoreActiveTextureUnitBinding(unsigned int target) = 0;
   virtual void RestoreFramebufferBindings() = 0;
 
   DISALLOW_COPY_AND_ASSIGN(GLStateRestorer);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_STATE_RESTORER_H_