chromium之ScopedNSAutoreleasePool浅析

上代码，看看注释

ScopedNSAutoreleasePool只有Mac系统特有的，也可以理解为OC特有的函数，

其他系统为空实现

// On the Mac, ScopedNSAutoreleasePool allocates an NSAutoreleasePool when
// instantiated and sends it a -drain message when destroyed.  This allows an
// autorelease pool to be maintained in ordinary C++ code without bringing in
// any direct Objective-C dependency.
//
// On other platforms, ScopedNSAutoreleasePool is an empty object with no
// effects.  This allows it to be used directly in cross-platform code without
// ugly #ifdefs.
class ScopedNSAutoreleasePool {
 public:
#if !defined(OS_MACOSX)
  ScopedNSAutoreleasePool() {}
  void Recycle() { }
#else  // OS_MACOSX
  ScopedNSAutoreleasePool();
  ~ScopedNSAutoreleasePool();

  // Clear out the pool in case its position on the stack causes it to be
  // alive for long periods of time (such as the entire length of the app).
  // Only use then when you're certain the items currently in the pool are
  // no longer needed.
  void Recycle();
 private:
  NSAutoreleasePool* autorelease_pool_;
#endif  // OS_MACOSX

 private:
  DISALLOW_COPY_AND_ASSIGN(ScopedNSAutoreleasePool);
};