Change scoped_ptr::reset()'s behaviour to match unique_ptr.

base/memory/scoped_ptr_unittest.cc

 // Copyright (c) 2012 The Chromium 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 "base/memory/scoped_ptr.h"
 
 #include <sstream>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 675 matching lines @@
 TEST(ScopedPtrTest, LoggingDoesntConvertToBoolean) {
   scoped_ptr<int> x(new int);
   std::stringstream s1;
   s1 << x;
 
   std::stringstream s2;
   s2 << x.get();
 
   EXPECT_EQ(s2.str(), s1.str());
 }
+
+TEST(ScopedPtrTest, ReferenceCycle) {
+  struct StructB;
+  struct StructA {
+    scoped_ptr<StructB> b;
+  };
+
+  struct StructB {
+    scoped_ptr<StructA> a;
+  };
+
+  // Create a reference cycle.
+  StructA* a = new StructA;
+  a->b.reset(new StructB);
+  a->b->a.reset(a);
+
+  // Break the cycle by calling |reset()|.

[Peter Kasting, 2015/09/23 03:09:44]

Nit: No || around function names

I might add to the end: "This will cause a->b to be deleted before the call to
reset() returns.  This tests that the implementation of scoped_ptr::reset()
doesn't access |this| after it deletes the underlying pointer."

[Anand Mistry (off Chromium), 2015/09/23 04:04:21]

Done and done.

+  a->b.reset();
+}