Ensure GL initialization only happens once, and provide common init path

ui/gl/gl_surface.h

Index: ui/gl/gl_surface.h
diff --git a/ui/gl/gl_surface.h b/ui/gl/gl_surface.h
index 8eaf60dab28c5c4d2db1bf12c17d27cd0a955c53..99052a90588708c7c626384ef0af2b9879cfeaed 100644
--- a/ui/gl/gl_surface.h
+++ b/ui/gl/gl_surface.h
@@ -70,6 +70,9 @@ class GL_EXPORT GLSurface : public base::RefCounted<GLSurface> {
   virtual bool PostSubBuffer(int x, int y, int width, int height);
 
   static bool InitializeOneOff();
+  static void InitializeOneOffForTests();
+  static void InitializeOneOffWithMockBindingsForTests();
+  static void InitializeDynamicMockBindingsForTests(GLContext* context);
 
   // Called after a context is made current with this surface. Returns false
   // on error.