Remove GLContext::Destroy

It should not be called explicitly. Make overrides private.

Review URL: https://codereview.chromium.org/1254383002

Cr-Commit-Position: refs/heads/master@{#340601}
diff --git a/ui/gl/gl_context_wgl.h b/ui/gl/gl_context_wgl.h
index ff0aae0d..21b3840 100644
--- a/ui/gl/gl_context_wgl.h
+++ b/ui/gl/gl_context_wgl.h
@@ -22,7 +22,6 @@
   // Implement GLContext.
   bool Initialize(GLSurface* compatible_surface,
                   GpuPreference gpu_preference) override;
-  void Destroy() override;
   bool MakeCurrent(GLSurface* surface) override;
   void ReleaseCurrent(GLSurface* surface) override;
   bool IsCurrent(GLSurface* surface) override;
@@ -32,6 +31,7 @@
 
  private:
   ~GLContextWGL() override;
+  void Destroy();
 
   HGLRC context_;