Replace SkFunction with std::function

tests/CPlusPlusEleven.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "Test.h"
 #include "SkTemplates.h"
-#include "SkFunction.h"
 
 namespace {
 class Moveable {
 public:
     Moveable() {}
     Moveable(Moveable&&) {}
     Moveable& operator=(Moveable&&) { return *this; }
 private:
     Moveable(const Moveable&);
     Moveable& operator=(const Moveable&);
@@ skipping 70 matching lines @@
     }
 
     {
         skstd::unique_ptr<const void, Deleter<const void>> u(new Moveable(), Deleter<const void>());
         static_assert(sizeof(u) == sizeof(SmallUniquePtr), TOO_BIG);
 
         auto u2 = skstd::move(u);
         static_assert(sizeof(u2) == sizeof(SmallUniquePtr), TOO_BIG);
     }
 }