Changed GpuVSyncProvider to implement gfx::VSyncProvider

ui/gl/vsync_provider_win.h

Index: ui/gl/vsync_provider_win.h
diff --git a/ui/gl/vsync_provider_win.h b/ui/gl/vsync_provider_win.h
index 8435fba662c1744b42c0814d4a0828dfdfe5456a..2a042a08b5fa29f5a70385c8fce7e8bae39a1488 100644
--- a/ui/gl/vsync_provider_win.h
+++ b/ui/gl/vsync_provider_win.h
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#ifndef UI_GL_VSYNC_PROVIDER_WIN_H_
+#define UI_GL_VSYNC_PROVIDER_WIN_H_
+
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/vsync_provider.h"
 #include "ui/gl/gl_export.h"
@@ -25,3 +28,5 @@ class GL_EXPORT VSyncProviderWin : public gfx::VSyncProvider {
 };
 
 }  // namespace gl
+
+#endif  // UI_GL_VSYNC_PROVIDER_WIN_H_