Add DeleteSoon(..., std::unique_ptr<T>)

There are cases where we want to delete an object held by a unique_ptr in
another thread. SequencedTaskRunner::DeleteSoon takes a raw pointer, which
means we need to call release(), like

task_runner->DeleteSoon(FROM_HERE, pointer.release());

This CL makes it possible to use std::move, like

task_runner->DeleteSoon(FROM_HERE, std::move(pointer));

Bug: None
Change-Id: I269d82547103ebe8c78c2498d269ba28ee5ca88f
Reviewed-on: https://chromium-review.googlesource.com/515264
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#474879}

base/sequenced_task_runner.h

@@ -5,6 +5,8 @@
 #ifndef BASE_SEQUENCED_TASK_RUNNER_H_
 #define BASE_SEQUENCED_TASK_RUNNER_H_
 
+#include <memory>
+
 #include "base/base_export.h"
 #include "base/callback.h"
 #include "base/sequenced_task_runner_helpers.h"
@@ -127,6 +129,12 @@ class BASE_EXPORT SequencedTaskRunner : public TaskRunner {
                                        object);
   }
 
+  template <class T>
+  bool DeleteSoon(const tracked_objects::Location& from_here,
+                  std::unique_ptr<T> object) {
+    return DeleteSoon(from_here, object.release());
+  }
+
   // Submits a non-nestable task to release the given object.  Returns
   // true if the object may be released at some point in the future,
   // and false if the object definitely will not be released.

content/public/browser/browser_thread.h

@@ -5,6 +5,7 @@
 #ifndef CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
 
+#include <memory>
 #include <string>
 #include <utility>
 
@@ -173,6 +174,13 @@ class CONTENT_EXPORT BrowserThread {
     return GetTaskRunnerForThread(identifier)->DeleteSoon(from_here, object);
   }
 
+  template <class T>
+  static bool DeleteSoon(ID identifier,
+                         const tracked_objects::Location& from_here,
+                         std::unique_ptr<T> object) {
+    return DeleteSoon(identifier, from_here, object.release());
+  }
+
   template <class T>
   static bool ReleaseSoon(ID identifier,
                           const tracked_objects::Location& from_here,