Route D3D VSync signal to Compositor

ui/gl/gl_switches.h

Index: ui/gl/gl_switches.h
diff --git a/ui/gl/gl_switches.h b/ui/gl/gl_switches.h
index 270b3fcd5c4c589731870c7c3035bcf03f84df93..945783b725a5244aeaa8cefcd88cf5c2d82ed579 100644
--- a/ui/gl/gl_switches.h
+++ b/ui/gl/gl_switches.h
@@ -7,6 +7,7 @@
 
 // Defines all the command-line switches used by ui/gl.
 
+#include "base/feature_list.h"
 #include "ui/gl/gl_export.h"
 
 namespace gl {
@@ -64,4 +65,12 @@ GL_EXPORT extern const int kGLSwitchesCopiedFromGpuProcessHostNumSwitches;
 
 }  // namespace switches
 
+namespace features {
+
+#if defined(OS_WIN)
+GL_EXPORT extern const base::Feature kD3DVsync;
+#endif  // defined(OS_WIN)
+
+}  // namespace features
+
 #endif  // UI_GL_GL_SWITCHES_H_