Revert of Move SkGLContext and some GrGLInterface implementations to skgputest module

include/gpu/gl/SkNullGLContext.h

Index: include/gpu/gl/SkNullGLContext.h
diff --git a/include/gpu/gl/SkNullGLContext.h b/include/gpu/gl/SkNullGLContext.h
new file mode 100644
index 0000000000000000000000000000000000000000..5a2a73fd8f54d73dbdbb8e25beda5a5becf04221
--- /dev/null
+++ b/include/gpu/gl/SkNullGLContext.h
@@ -0,0 +1,26 @@
+
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef SkNullGLContext_DEFINED
+#define SkNullGLContext_DEFINED
+
+#include "gl/SkGLContext.h"
+
+class SK_API SkNullGLContext : public SkGLContext {
+public:
+    ~SkNullGLContext() override;
+    static SkNullGLContext* Create();
+
+private:
+    SkNullGLContext();
+
+    void onPlatformMakeCurrent() const override {};
+    void onPlatformSwapBuffers() const override {}
+    GrGLFuncPtr onPlatformGetProcAddress(const char*) const override { return nullptr; }
+};
+
+#endif