Convert various ReleaseSoon methods to use base::Bind()

BUG=none
TEST=none
TBR=brettw,atwilson

Review URL: http://codereview.chromium.org/9022034

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@116030 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 46 insertions, 15 deletions

diff --git a/base/message_loop_helpers.h b/base/message_loop_helpers.h
index 151128c..9aeaad7 100644
--- a/base/message_loop_helpers.h
+++ b/base/message_loop_helpers.h
@@ -16,17 +16,18 @@ namespace base {
 
 namespace subtle {
 template <class T, class R> class DeleteHelperInternal;
+template <class T, class R> class ReleaseHelperInternal;
 }
 
-// This is a template helper which uses a function indirection to erase T from
-// the function signature while still remembering it so we can call the correct
-// destructor. We use this trick so we don't need to include bind.h in a
-// header file. We also embed the function in a class to make it easier for
-// users of DeleteSoon to declare the helper as a friend.
+// Template helpers which use a function indirection to erase T from the
+// function signature while still remembering it so we can call the correct
+// destructor/release function.
+// We use this trick so we don't need to include bind.h in a header file like
+// message_loop.h. We also wrap the helpers in a templated class to make it
+// easier for users of DeleteSoon to declare the helper as a friend.
 template <class T>
 class DeleteHelper {
  private:
-  // TODO(dcheng): Move the return type back to a function template parameter.
   template <class T2, class R> friend class subtle::DeleteHelperInternal;
 
   static void DoDelete(const void* object) {
@@ -36,19 +37,32 @@ class DeleteHelper {
   DISALLOW_COPY_AND_ASSIGN(DeleteHelper);
 };
 
+template <class T>
+class ReleaseHelper {
+ private:
+  template <class T2, class R> friend class subtle::ReleaseHelperInternal;
+
+  static void DoRelease(const void* object) {
+    reinterpret_cast<const T*>(object)->Release();
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(ReleaseHelper);
+};
+
 namespace subtle {
 
-// An internal MessageLoop-like class helper for DeleteHelper. We don't want to
-// expose DoDelete directly since the void* argument makes it possible to pass
-// an object of the wrong type to delete. Instead, we force callers to go
-// through DeleteHelperInternal for type safety. MessageLoop-like classes which
-// expose a DeleteSoon method should friend this class and implement a
-// DeleteSoonInternal method with the following signature:
+// An internal MessageLoop-like class helper for DeleteHelper and ReleaseHelper.
+// We don't want to expose the Do*() functions directly directly since the void*
+// argument makes it possible to pass/ an object of the wrong type to delete.
+// Instead, we force callers to go through these internal helpers for type
+// safety. MessageLoop-like classes which expose DeleteSoon or ReleaseSoon
+// methods should friend the appropriate helper and implement a corresponding
+// *Internal method with the following signature:
 // bool(const tracked_objects::Location&,
-//      void(*deleter)(const void*),
+//      void(*function)(const void*),
 //      void* object)
-// An implementation of DeleteSoonInternal should simply create a base::Closure
-// from (deleter, object) and return the result of posting the task.
+// An implementation of this function should simply create a base::Closure
+// from (function, object) and return the result of posting the task.
 template <class T, class ReturnType>
 class DeleteHelperInternal {
  public:
@@ -66,6 +80,23 @@ class DeleteHelperInternal {
   DISALLOW_COPY_AND_ASSIGN(DeleteHelperInternal);
 };
 
+template <class T, class ReturnType>
+class ReleaseHelperInternal {
+ public:
+  template <class MessageLoopType>
+  static ReturnType ReleaseOnMessageLoop(
+      MessageLoopType* message_loop,
+      const tracked_objects::Location& from_here,
+      const T* object) {
+    return message_loop->ReleaseSoonInternal(from_here,
+                                             &ReleaseHelper<T>::DoRelease,
+                                             object);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ReleaseHelperInternal);
+};
+
 }  // namespace subtle
 
 }  // namespace base