Restore only modified texture state during virtual context switches

ui/gl/gl_gl_api_implementation.h

Index: ui/gl/gl_gl_api_implementation.h
diff --git a/ui/gl/gl_gl_api_implementation.h b/ui/gl/gl_gl_api_implementation.h
index d925b939909c8bd1a51058f31c2a8de1b4390beb..7a9acf37593dc3a01ded3b6fcd7356a60c4eb90b 100644
--- a/ui/gl/gl_gl_api_implementation.h
+++ b/ui/gl/gl_gl_api_implementation.h
@@ -6,6 +6,7 @@
 #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"
 
@@ -80,8 +81,13 @@ class GL_EXPORT VirtualGLApi : public GLApiBase {
 
   // 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_;
 
@@ -90,6 +96,12 @@ class GL_EXPORT VirtualGLApi : public GLApiBase {
 
   // 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