Revert of Make SkGLContext lifetime more well-defined

include/gpu/gl/SkGLContext.h

Index: include/gpu/gl/SkGLContext.h
diff --git a/include/gpu/gl/SkGLContext.h b/include/gpu/gl/SkGLContext.h
index 7edfa730aa746ac33e3366e327645df9f38aeea7..3420a47973228594d4d1f8f6fc24cca9df685f3c 100644
--- a/include/gpu/gl/SkGLContext.h
+++ b/include/gpu/gl/SkGLContext.h
@@ -17,9 +17,9 @@
  * This class is intended for Skia's testing needs and not for general
  * use.
  */
-class SK_API SkGLContext : public SkNoncopyable {
+class SK_API SkGLContext : public SkRefCnt {
 public:
-    virtual ~SkGLContext();
+    ~SkGLContext() override;
 
     bool isValid() const { return NULL != gl(); }
 
@@ -106,6 +106,8 @@
     SkAutoTUnref<const GrGLInterface> fGL;
 
     friend class GLFenceSync;  // For onPlatformGetProcAddress.
+
+    typedef SkRefCnt INHERITED;
 };
 
 /** Creates platform-dependent GL context object