Catch stray Retains() and Releases() outside of RetainPtr<>.

core/fxcrt/cfx_retain_ptr_unittest.cpp

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/fxcrt/cfx_retain_ptr.h"
 
 #include <utility>
 
 #include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 class PseudoRetainable {
  public:
   PseudoRetainable() : retain_count_(0), release_count_(0) {}
-  void Retain() { ++retain_count_; }
-  void Release() { ++release_count_; }
   int retain_count() const { return retain_count_; }
   int release_count() const { return release_count_; }
 
  private:
+  template <typename U>
+  friend struct ::ReleaseDeleter;
+  template <typename U>
+  friend class ::CFX_RetainPtr;
+
+  void Retain() { ++retain_count_; }
+  void Release() { ++release_count_; }
+
   int retain_count_;
   int release_count_;
 };
 
 }  // namespace
 
 TEST(fxcrt, RetainPtrNull) {
   CFX_RetainPtr<PseudoRetainable> ptr;
   EXPECT_EQ(nullptr, ptr.Get());
 }
@@ skipping 183 matching lines @@
 
 TEST(fxcrt, RetainPtrMakeRetained) {
   auto ptr = pdfium::MakeRetain<CFX_Retainable>();
   EXPECT_TRUE(ptr->HasOneRef());
   {
     CFX_RetainPtr<CFX_Retainable> other = ptr;
     EXPECT_FALSE(ptr->HasOneRef());
   }
   EXPECT_TRUE(ptr->HasOneRef());
 }