[Mac] Capture -dealloc backtrace to log with CrZombie messages.

base/debug/stack_trace.h

 // Copyright (c) 2011 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.
 
 #ifndef BASE_DEBUG_STACK_TRACE_H_
 #define BASE_DEBUG_STACK_TRACE_H_
 #pragma once
 
 #include <iosfwd>
 
 #include "base/base_export.h"
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 struct _EXCEPTION_POINTERS;
 #endif
 
 namespace base {
 namespace debug {
 
 // A stacktrace can be helpful in debugging. For example, you can include a
 // stacktrace member in a object (probably around #ifndef NDEBUG) so that you
 // can later see where the given object was created from.
 class BASE_EXPORT StackTrace {
  public:
   // Creates a stacktrace from the current location.
   StackTrace();
 
+  // Creates a stacktrace from an existing array of instruction
+  // pointers (such as returned by Addresses()).  |count| will be
+  // trimmed to |kMaxTraces|.
+  StackTrace(const void* const* trace, int count);
+
 #if defined(OS_WIN)
   // Creates a stacktrace for an exception.
   // Note: this function will throw an import not found (StackWalk64) exception
   // on system without dbghelp 5.1.
   StackTrace(_EXCEPTION_POINTERS* exception_pointers);
 #endif
 
   // Copying and assignment are allowed with the default functions.
 
   ~StackTrace();
 
   // Gets an array of instruction pointer values. |*count| will be set to the
   // number of elements in the returned array.
   const void* const* Addresses(size_t* count) const;
 
   // Prints a backtrace to stderr
   void PrintBacktrace() const;
 
   // Resolves backtrace to symbols and write to stream.
   void OutputToStream(std::ostream* os) const;
 
  private:
   // From http://msdn.microsoft.com/en-us/library/bb204633.aspx,
   // the sum of FramesToSkip and FramesToCapture must be less than 63,
   // so set it to 62. Even if on POSIX it could be a larger value, it usually
   // doesn't give much more information.
   static const int kMaxTraces = 62;
 
   void* trace_[kMaxTraces];
   int count_;

[Scott Hess - ex-Googler, 2011/08/29 20:13:36]

Having this and kMaxTraces be int seems wrong, would you mind if I switch to
size_t while I'm in here?  The code itself seems unclear on the difference
between int and size_t (f/i, Addresses() has if(count_) and has a size_t*
parameter).  I could land it as a followup CL, in the interests of landing the
rest sooner rather than later.

 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_STACK_TRACE_H_