Restore only modified texture state during virtual context switches

ui/gl/dirty_texture_state.h

Index: ui/gl/dirty_texture_state.h
diff --git a/ui/gl/dirty_texture_state.h b/ui/gl/dirty_texture_state.h
new file mode 100644
index 0000000000000000000000000000000000000000..a839142d6d670ab4afcfdd562b77e9eb9ff7d8a8
--- /dev/null
+++ b/ui/gl/dirty_texture_state.h
@@ -0,0 +1,59 @@
+// Copyright (c) 2013 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_DIRTY_TEXTURE_STATE_H_
+#define UI_GL_DIRTY_TEXTURE_STATE_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "ui/gl/gl_bindings.h"
+#include "ui/gl/gl_export.h"
+
+namespace gfx {
+
+struct DirtyTextureBindings {
+  bool binding_2d;
+  bool binding_cube_map;
+  bool binding_external_oes;
+  bool binding_rectangle_arb;
+  DirtyTextureBindings() : binding_2d(false),
+                           binding_cube_map(false),
+                           binding_external_oes(false),
+                           binding_rectangle_arb(false) {
+  }
+};
+
+class DirtyTextureState {
+ public:
+  DirtyTextureState();
+  ~DirtyTextureState();
+
+  void UpdateMaxTextureUnit(GLenum texture_unit);
+  void AddBinding(GLuint current_unit, GLenum target);
+  void Clear();
+  int GetMaxTextureUnitIndex() const { return max_texture_unit_ - GL_TEXTURE0; }
+  bool IsBinding2DDirtyForUnit(GLuint unit) const {
+    return bindings_[unit].binding_2d;
+  }
+  bool IsBindingCubeMapDirtyForUnit(GLuint unit) const {
+    return bindings_[unit].binding_cube_map;
+  }
+  bool IsBindingExternalOesDirtyForUnit(GLuint unit) const {
+    return bindings_[unit].binding_external_oes;
+  }
+  bool IsBindingRectangleArbDirtyForUnit(GLuint unit) const {
+    return bindings_[unit].binding_rectangle_arb;
+  }
+
+ private:
+  std::vector<DirtyTextureBindings> bindings_;
+  GLenum max_texture_unit_;
+
+  DISALLOW_COPY_AND_ASSIGN(DirtyTextureState);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GL_DIRTY_TEXTURE_STATE_H_