Replace MessageLoop::DeleteSoon implementation with one that uses base::Bind.

base/message_loop.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_MESSAGE_LOOP_H_
 #define BASE_MESSAGE_LOOP_H_
 #pragma once
 
 #include <queue>
 #include <string>
@@ skipping 26 matching lines @@
 #include "base/message_pump_x.h"
 #else
 #include "base/message_pump_gtk.h"
 #endif
 
 #endif
 #endif
 
 namespace base {
 class Histogram;
+
+template <class T>

[awong, 2011/12/28 23:24:19]

This needs a comment explaining why we need this.

Basically, we need a template helper to "erase" T from the signature, while
still remembering it for use with deleting a pointer.  Embedding this in a class
makes it easier for users of DeleteSoon, etc., to declare this as a friend. And
lastly, no one but MessageLoop should call DoDelete.

BTW, is it worth making DoDelete() private and friending MessageLoop?

[dcheng, 2011/12/28 23:34:20]

Done. As discussed, made DoDelete private as well since all locations that
directly use DeleteTask will be converted to use DeleteSoon.

+class DeleteHelper {
+ public:
+  static void DoDelete(const void* object) {
+    delete reinterpret_cast<const T*>(object);
+  }
+};
 }
 
 // A MessageLoop is used to process events for a particular thread.  There is
 // at most one MessageLoop instance per thread.
 //
 // Events include at a minimum Task instances submitted to PostTask or those
 // managed by TimerManager.  Depending on the type of message pump used by the
 // MessageLoop other events such as UI messages may be processed.  On Windows
 // APC calls (as time permits) and signals sent to a registered set of HANDLEs
 // may also be processed.
@@ skipping 144 matching lines @@
   // if the object needs to live until the next run of the MessageLoop (for
   // example, deleting a RenderProcessHost from within an IPC callback is not
   // good).
   //
   // NOTE: This method may be called on any thread.  The object will be deleted
   // on the thread that executes MessageLoop::Run().  If this is not the same
   // as the thread that calls PostDelayedTask(FROM_HERE, ), then T MUST inherit
   // from RefCountedThreadSafe<T>!
   template <class T>
   void DeleteSoon(const tracked_objects::Location& from_here, const T* object) {
-    PostNonNestableTask(from_here, new DeleteTask<T>(object));
+    DeleteSoonInternal(from_here, &base::DeleteHelper<T>::DoDelete, object);
   }
 
   // A variant on PostTask that releases the given reference counted object
   // (by calling its Release method).  This is useful if the object needs to
   // live until the next run of the MessageLoop, or if the object needs to be
   // released on a particular thread.
   //
   // NOTE: This method may be called on any thread.  The object will be
   // released (and thus possibly deleted) on the thread that executes
   // MessageLoop::Run().  If this is not the same as the thread that calls
@@ skipping 303 matching lines @@
 
   // The next sequence number to use for delayed tasks.
   int next_sequence_num_;
 
   ObserverList<TaskObserver> task_observers_;
 
   // The message loop proxy associated with this message loop, if one exists.
   scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
 
  private:
+  void DeleteSoonInternal(const tracked_objects::Location& from_here,
+                          void(*deleter)(const void*),
+                          const void* object);
+
   DISALLOW_COPY_AND_ASSIGN(MessageLoop);
 };
 
 //-----------------------------------------------------------------------------
 // MessageLoopForUI extends MessageLoop with methods that are particular to a
 // MessageLoop instantiated with TYPE_UI.
 //
 // This class is typically used like so:
 //   MessageLoopForUI::current()->...call some method...
 //
@@ skipping 111 matching lines @@
 #endif  // defined(OS_POSIX)
 };
 
 // Do not add any member variables to MessageLoopForIO!  This is important b/c
 // MessageLoopForIO is often allocated via MessageLoop(TYPE_IO).  Any extra
 // data that you need should be stored on the MessageLoop's pump_ instance.
 COMPILE_ASSERT(sizeof(MessageLoop) == sizeof(MessageLoopForIO),
                MessageLoopForIO_should_not_have_extra_member_variables);
 
 #endif  // BASE_MESSAGE_LOOP_H_