Replace GrGLInterface's function pointers with std::functions

include/gpu/gl/GrGLExtensions.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLExtensions_DEFINED
 #define GrGLExtensions_DEFINED
 
@@ skipping 21 matching lines @@
         fStrings.swap(that->fStrings);
         SkTSwap(fInitialized, that->fInitialized);
     }
 
     /**
      * We sometimes need to use this class without having yet created a GrGLInterface. This version
      * of init expects that getString is always non-NULL while getIntegerv and getStringi are non-
      * NULL if on desktop GL with version 3.0 or higher. Otherwise it will fail.
      */
     bool init(GrGLStandard standard,
-              GrGLGetStringProc getString,
-              GrGLGetStringiProc getStringi,
-              GrGLGetIntegervProc getIntegerv,
-              GrEGLQueryStringProc queryString = nullptr,
+              GrGLFunction<GrGLGetStringProc> getString,
+              GrGLFunction<GrGLGetStringiProc> getStringi,
+              GrGLFunction<GrGLGetIntegervProc> getIntegerv,
+              GrGLFunction<GrEGLQueryStringProc> queryString = nullptr,
               GrEGLDisplay eglDisplay = nullptr);
 
     bool isInitialized() const { return fInitialized; }
 
     /**
      * Queries whether an extension is present. This will fail if init() has not been called.
      */
     bool has(const char[]) const;
 
     /**
      * Removes an extension if present. Returns true if the extension was present before the call.
      */
     bool remove(const char[]);
 
     /**
      * Adds an extension to list
      */
     void add(const char[]);
 
     void reset() { fStrings->reset(); }
 
     void print(const char* sep = "\n") const;
 
 private:
     bool                                fInitialized;
     SkAutoTDelete<SkTArray<SkString> >  fStrings;
 };
 
 #endif