Add OnceCallback support to PostTaskAndReplyWithResult

content/public/browser/browser_thread.h

 // Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
 
 #include <string>
 #include <utility>
 
@@ skipping 124 matching lines @@
 
   static bool PostTaskAndReply(ID identifier,
                                const tracked_objects::Location& from_here,
                                base::OnceClosure task,
                                base::OnceClosure reply);
 
   template <typename ReturnType, typename ReplyArgType>
   static bool PostTaskAndReplyWithResult(
       ID identifier,
       const tracked_objects::Location& from_here,
-      base::Callback<ReturnType()> task,
-      base::Callback<void(ReplyArgType)> reply) {
+      base::OnceCallback<ReturnType()> task,
+      base::OnceCallback<void(ReplyArgType)> reply) {
     scoped_refptr<base::SingleThreadTaskRunner> task_runner =
         GetTaskRunnerForThread(identifier);
     return base::PostTaskAndReplyWithResult(task_runner.get(), from_here,
                                             std::move(task), std::move(reply));
   }
 
+  // Callback version of PostTaskAndReplyWithResult above.
+  // Though RepeatingCallback is convertible to OnceCallback, we need this since
+  // we can not use template deduction and object conversion at once on the
+  // overload resolution.
+  // TODO(tzik): Update all callers of the Callback version to use OnceCallback.

[kinuko, 2017/05/01 04:48:47]

nit: link to the issue?

[tzik, 2017/05/01 05:13:01]

Done.

+  template <typename ReturnType, typename ReplyArgType>
+  static bool PostTaskAndReplyWithResult(
+      ID identifier,
+      const tracked_objects::Location& from_here,
+      base::Callback<ReturnType()> task,
+      base::Callback<void(ReplyArgType)> reply) {
+    return PostTaskAndReplyWithResult(
+        identifier, from_here,
+        static_cast<base::OnceCallback<ReturnType()>>(std::move(task)),
+        static_cast<base::OnceCallback<void(ReplyArgType)>>(std::move(reply)));
+  }
+
   template <class T>
   static bool DeleteSoon(ID identifier,
                          const tracked_objects::Location& from_here,
                          const T* object) {
     return GetTaskRunnerForThread(identifier)->DeleteSoon(from_here, object);
   }
 
   template <class T>
   static bool ReleaseSoon(ID identifier,
                           const tracked_objects::Location& from_here,
@@ skipping 159 matching lines @@
  private:
   friend class BrowserThreadImpl;
 
   BrowserThread() {}
   DISALLOW_COPY_AND_ASSIGN(BrowserThread);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_