Update scoped_array<T>::reset logic to match scoped_ptr.

base/memory/scoped_ptr.h

 // 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.
 
 // Scopers help you manage ownership of a pointer, helping you easily manage the
 // a pointer within a scope, and automatically destroying the pointer at the
 // end of a scope.  There are two main classes you will use, which correspond
 // to the operators new/delete and new[]/delete[].
 //
 // Example usage (scoped_ptr):
@@ skipping 588 matching lines @@
     enum { type_must_be_complete = sizeof(C) };
     delete[] array_;
   }
 
   // operator=.  Move operator= for C++03 move emulation of this type.
   scoped_array& operator=(RValue rhs) {
     reset(rhs.object->release());
     return *this;
   }
 
-  // Reset.  Deletes the current owned object, if any.
-  // Then takes ownership of a new object, if given.
-  // this->reset(this->get()) works.
+  // Reset. Deletes the current owned object, if any.
   void reset(C* p = NULL) {
-    if (p != array_) {
-      enum { type_must_be_complete = sizeof(C) };
-      delete[] array_;
-      array_ = p;
-    }
+    // This is a self-reset, which is no longer allowed: http://crbug.com/162971
+    if (p != NULL && p == array_)
+      abort();
+
+    C* old = array_;
+    array_ = NULL;
+    if (old != NULL)
+      delete[] old;
+    array_ = p;
   }
 
   // Get one element of the current object.
   // Will assert() if there is no current object, or index i is negative.
   C& operator[](ptrdiff_t i) const {
     assert(i >= 0);
     assert(array_ != NULL);
     return array_[i];
   }
 
@@ skipping 186 matching lines @@
 
 // A function to convert T* into scoped_ptr<T>
 // Doing e.g. make_scoped_ptr(new FooBarBaz<type>(arg)) is a shorter notation
 // for scoped_ptr<FooBarBaz<type> >(new FooBarBaz<type>(arg))
 template <typename T>
 scoped_ptr<T> make_scoped_ptr(T* ptr) {
   return scoped_ptr<T>(ptr);
 }
 
 #endif  // BASE_MEMORY_SCOPED_PTR_H_