Make the debug interface a GrGLTestInterface subclass.

src/gpu/gl/debug/GrTextureUnitObj.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextureUnitObj_DEFINED
 #define GrTextureUnitObj_DEFINED
 
 #include "GrFakeRefObj.h"
 class GrTextureObj;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Although texture unit objects are allocated & deallocated like the other
 // GL emulation objects they are derived from GrFakeRefObj to provide some
-// uniformity in how the GrDebugGL class manages resources
+// uniformity in how the debug interface class manages resources
 class GrTextureUnitObj : public GrFakeRefObj {
     GR_DEFINE_CREATOR(GrTextureUnitObj);
 
 public:
     GrTextureUnitObj()
         : GrFakeRefObj()
         , fNumber(0)
         , fTexture(nullptr) {
     }
 
     void setNumber(GrGLenum number) {
         fNumber = number;
     }
     GrGLenum getNumber() const { return fNumber; }
 
     void setTexture(GrTextureObj *texture);
     GrTextureObj *getTexture()                  { return fTexture; }
 
 protected:
 private:
     GrGLenum fNumber;
     GrTextureObj *fTexture;
 
     typedef GrFakeRefObj INHERITED;
 };
 
 #endif // GrTextureUnitObj_DEFINED