Restore only modified texture state during virtual context switches

ui/gl/gl_gl_api_implementation.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_API_IMPLEMENTATION_H_
 #define UI_GL_GL_API_IMPLEMENTATION_H_
 
 #include "base/compiler_specific.h"
+#include "ui/gl/dirty_texture_state.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_export.h"
 
 namespace gpu {
 namespace gles2 {
 class GLES2Decoder;
 }
 }
 namespace gfx {
 
@@ skipping 54 matching lines @@
   virtual ~VirtualGLApi();
   void Initialize(DriverGL* driver, GLContext* real_context);
 
   // Sets the current virutal context.
   bool MakeCurrent(GLContext* virtual_context, GLSurface* surface);
 
   void OnReleaseVirtuallyCurrent(GLContext* virtual_context);
 
   // Overridden functions from GLApiBase
   virtual const GLubyte* glGetStringFn(GLenum name) OVERRIDE;
+  virtual void glActiveTextureFn(GLenum texture) OVERRIDE;
+  virtual void glBindTextureFn(GLenum target, GLuint texture) OVERRIDE;
 
  private:
+  // Clears the dirty texture state associated with this virtual context.
+  void ClearDirtyTextureState();
+
   // The real context we're running on.
   GLContext* real_context_;
 
   // The current virtual context.
   GLContext* current_context_;
 
   // The supported extensions being advertised for this virtual context.
   std::string extensions_;
+
+  // Current active texture unit.
+  GLenum current_active_texture_unit_;
+
+  // The texture state that has been modified by this virtual context.
+  DirtyTextureState dirty_texture_state_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_API_IMPLEMENTATION_H_