minidump: Change the ownership model

minidump/minidump_writable.h

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 115 matching lines @@
     //! most other data, memory snapshots are large and the entire snapshots do
     //! not need to be consulted in order to process a minidump file.
     kPhaseLate,
   };
 
   //! \brief A size value used to signal failure by methods that return
   //!     `size_t`.
   static const size_t kInvalidSize;
 
   MinidumpWritable();
-  ~MinidumpWritable();
+
+  // This doesn’t really need to be virtual because nothing ever deletes a
+  // MinidumpWritable* through an interface pointer with that type, and this is
+  // guaranteed by being protected. Regardless, the style guide is somewhat
+  // insistent.
+  // http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Inheritance
+  virtual ~MinidumpWritable();
 
   //! \brief The state of the object.
   State state() const { return state_; }
 
   //! \brief Transitions the object from #kStateMutable to #kStateFrozen.
   //!
   //! The default implementation marks the object as frozen and recursively
   //! calls Freeze() on all of its children. Subclasses may override this method
   //! to perform processing that should only be done once callers have finished
   //! populating an object with data. Typically, a subclass implementation would
@@ skipping 120 matching lines @@
   size_t leading_pad_bytes_;
   State state_;
 
   DISALLOW_COPY_AND_ASSIGN(MinidumpWritable);
 };
 
 }  // namespace internal
 }  // namespace crashpad
 
 #endif  // CRASHPAD_MINIDUMP_MINIDUMP_WRITABLE_H_