Fixed example in MessageLoop::ReleaseSoon comment

base/message_loop/message_loop.h

Index: base/message_loop/message_loop.h
diff --git a/base/message_loop/message_loop.h b/base/message_loop/message_loop.h
index 25891c5dc7c7c4866a5b865b8b1cc13f9092daaa..7dafdeaf18538fba7b444c2bfa90a00b17b80648 100644
--- a/base/message_loop/message_loop.h
+++ b/base/message_loop/message_loop.h
@@ -214,9 +214,10 @@ class BASE_EXPORT MessageLoop : public MessagePump::Delegate {
   // example:
   //
   // scoped_refptr<Foo> foo = ...
-  // foo.AddRef();
-  // message_loop->ReleaseSoon(foo.get());
+  // foo->AddRef();
+  // Foo* raw_foo = foo.get();
   // foo = NULL;

[Mark Mentovai, 2014/05/29 20:42:10]

If everything is RefCountedThreadSafe, why should it matter whether this happens
before or after the call to ReleaseSoon?

[maniscalco, 2014/05/29 22:50:31]

Here's my understanding.  vkuzkokov, correct me if I'm wrong.

In the example code I committed, foo was not cleared until *after* ReleaseSoon()
was called.  Under the covers, ReleaseSoon() will post a task to message_loop. 
If the message_loop thread is "really fast", it could finish executing the
Release() *before* ReleaseSoon() has even returned.  If this happens, foo will
be the last reference and clearing it will destroy the object.

Destroying the Foo here would be bad because the reason for using ReleaseSoon()
in the first place was to ensure it gets destroyed in some other thread (in this
case, message_loop).

+  // message_loop->ReleaseSoon(raw_foo);
   //
   // NOTE: This method may be called on any thread.  The object will be
   // released (and thus possibly deleted) on the thread that executes