Implement scoped_const_refptr template.

webrtc/base/bind_unittest.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 39 matching lines @@
 struct E: public D {
   int Release();
 };
 struct F {
   void AddRef();
   void Release();
 };
 
 struct LifeTimeCheck {
   LifeTimeCheck() : ref_count_(0) {}
-  void AddRef() { ++ref_count_; }
-  void Release() { --ref_count_; }
+  void AddRef() const { ++ref_count_; }
+  void Release() const { --ref_count_; }
   void NullaryVoid() {}
-  int ref_count_;
+  mutable int ref_count_;
 };
 
 int Return42() { return 42; }
 int Negate(int a) { return -a; }
 int Multiply(int a, int b) { return a * b; }
 
 }  // namespace
 
 // Try to catch any problem with scoped_refptr type deduction in rtc::Bind at
 // compile time.
@@ skipping 155 matching lines @@
 // modified to a non-reference capture.
 TEST(BindTest, RefArgument) {
   const int x = 42;
   EXPECT_EQ(&x, Ref(x));
   // Bind() should make a copy of |x|, i.e. the pointers should be different.
   auto functor = Bind(&Ref, x);
   EXPECT_NE(&x, functor());
 }
 
 }  // namespace rtc