Force HostContentSettingsMap to be destroyed on its owning thread.

components/keyed_service/core/refcounted_keyed_service.cc

 // Copyright 2014 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.
 
 #include "components/keyed_service/core/refcounted_keyed_service.h"
 
-#include "base/location.h"
-#include "base/threading/thread_task_runner_handle.h"
+#include <utility>
+
+#include "base/threading/sequenced_task_runner_handle.h"
 
 namespace impl {
 
 // static
 void RefcountedKeyedServiceTraits::Destruct(const RefcountedKeyedService* obj) {
   if (obj->task_runner_.get() != nullptr &&
-      obj->task_runner_.get() != base::ThreadTaskRunnerHandle::Get()) {
+      base::SequencedTaskRunnerHandle::IsSet() &&
+      obj->task_runner_.get() != base::SequencedTaskRunnerHandle::Get()) {

[Bernhard Bauer, 2016/12/19 17:07:29]

Do we have a guarantee that STRH's can be compared by address?

[gab, 2016/12/19 18:25:56]

No we don't (in practice it's true for MessageLoop and TaskScheduler, but not
for SequencedWorkerPool). But it's fine as worst case is a false negative where
we post to self.

You make me think though, the right thing here is to just use
obj->task_runner_->RunsTasksOnCurrentThread().

     obj->task_runner_->DeleteSoon(FROM_HERE, obj);
   } else {
     delete obj;
   }
 }
 
 }  // namespace impl
 
 RefcountedKeyedService::RefcountedKeyedService() : task_runner_(nullptr) {
 }
 
 RefcountedKeyedService::RefcountedKeyedService(
-    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
-    : task_runner_(task_runner) {
-}
+    scoped_refptr<base::SequencedTaskRunner> task_runner)
+    : task_runner_(std::move(task_runner)) {}
 
-RefcountedKeyedService::~RefcountedKeyedService() {
-}
+RefcountedKeyedService::~RefcountedKeyedService() = default;