Split DirectCompositionSurfaceWin into two parts.

ui/gl/scoped_make_current.h

Index: ui/gl/scoped_make_current.h
diff --git a/ui/gl/scoped_make_current.h b/ui/gl/scoped_make_current.h
index fb25fc08ce28cc8bca3bb1215e605e5c14849ab1..ba50583c618200907c87a343f62d8b152c62b5bb 100644
--- a/ui/gl/scoped_make_current.h
+++ b/ui/gl/scoped_make_current.h
@@ -7,6 +7,7 @@
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/optional.h"
 #include "ui/gl/gl_export.h"
 
 namespace gl {
@@ -33,6 +34,20 @@ class GL_EXPORT ScopedMakeCurrent {
   DISALLOW_COPY_AND_ASSIGN(ScopedMakeCurrent);
 };
 
+// This class is used to make sure a specified surface isn't current, and upon
+// destruction it will make the surface current again if it had been before.
+class GL_EXPORT ScopedReleaseCurrent {
+ public:
+  explicit ScopedReleaseCurrent(gl::GLSurface* this_surface);
+
+  ~ScopedReleaseCurrent();
+
+ private:
+  base::Optional<ScopedMakeCurrent> make_current_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedReleaseCurrent);
+};
+
 }  // namespace ui
 
 #endif  // UI_GL_SCOPED_MAKE_CURRENT_H_