Fix shutdown crash in settings app monitor.

chrome/browser/win/settings_app_monitor.cc

 // Copyright 2016 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 "chrome/browser/win/settings_app_monitor.h"
 
 #include <atlbase.h>
 #include <atlcom.h>
 #include <oleauto.h>
 #include <stdint.h>
@@ skipping 36 matching lines @@
   // Deletes the instance.
   void DeleteOnAutomationThread();
 
   // Initializes the context, invoking the monitor's |OnInitialized| method via
   // |monitor_runner| when done. On success, the monitor's other On* methods
   // will be invoked as events are observed. On failure, this instance
   // self-destructs after posting |init_callback|. |task_runner| is the runner
   // for the dedicated thread on which the context lives (owned by its
   // UIAutomationClient).
   void Initialize(base::SingleThreadTaskRunner* task_runner,
-                  base::SequencedTaskRunner* monitor_runner,
+                  scoped_refptr<base::SequencedTaskRunner> monitor_runner,
                   const base::WeakPtr<SettingsAppMonitor>& monitor);
 
  private:
   class EventHandler;
 
   // The one and only method that may be called from outside of the automation
   // thread.
   Context();
   ~Context();
 
@@ skipping 21 matching lines @@
   base::win::ScopedComPtr<IUIAutomationFocusChangedEventHandler>
   GetFocusChangedEventHandler();
 
   // Installs an event handler to observe events of interest.
   HRESULT InstallObservers();
 
   // The task runner for the automation thread.
   base::SingleThreadTaskRunner* task_runner_ = nullptr;
 
   // The task runner on which the owning monitor lives.
-  base::SequencedTaskRunner* monitor_runner_ = nullptr;
+  scoped_refptr<base::SequencedTaskRunner> monitor_runner_ = nullptr;
 
   // The monitor that owns this context.
   base::WeakPtr<SettingsAppMonitor> monitor_;
 
   // The automation client.
   base::win::ScopedComPtr<IUIAutomation> automation_;
 
   // The event handler.
   base::win::ScopedComPtr<IUnknown> event_handler_;
 
@@ skipping 447 matching lines @@
   return context->weak_ptr_factory_.GetWeakPtr();
 }
 
 void SettingsAppMonitor::Context::DeleteOnAutomationThread() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   delete this;
 }
 
 void SettingsAppMonitor::Context::Initialize(
     base::SingleThreadTaskRunner* task_runner,
-    base::SequencedTaskRunner* monitor_runner,
+    scoped_refptr<base::SequencedTaskRunner> monitor_runner,
     const base::WeakPtr<SettingsAppMonitor>& monitor) {
   // This and all other methods must be called on the automation thread.
   DCHECK(task_runner->BelongsToCurrentThread());
   DCHECK(!monitor_runner->RunsTasksOnCurrentThread());
 
   task_runner_ = task_runner;
   monitor_runner_ = monitor_runner;
   monitor_ = monitor;
 
   HRESULT result = automation_.CreateInstance(CLSID_CUIAutomation, nullptr,
@@ skipping 120 matching lines @@
       weak_ptr_factory_(this) {
   ui::win::CreateATLModuleIfNeeded();
   // Start the automation thread and initialize the automation client on it.
   context_ = Context::Create();
   automation_thread_.init_com_with_mta(true);
   automation_thread_.Start();
   automation_thread_.task_runner()->PostTask(
       FROM_HERE,
       base::Bind(&SettingsAppMonitor::Context::Initialize, context_,
                  base::Unretained(automation_thread_.task_runner().get()),
-                 base::Unretained(base::SequencedTaskRunnerHandle::Get().get()),
+                 base::SequencedTaskRunnerHandle::Get(),
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 SettingsAppMonitor::~SettingsAppMonitor() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // context_ is still valid when the caller destroys the instance before the
   // callback(s) have fired. In this case, delete the context on the automation
   // thread before joining with it. DeleteSoon is not used because the monitor
   // has only a WeakPtr to the context that is bound to the automation thread.
@@ skipping 18 matching lines @@
   delegate_->OnChooserInvoked();
 }
 
 void SettingsAppMonitor::OnBrowserChosen(const base::string16& browser_name) {
   DCHECK(thread_checker_.CalledOnValidThread());
   delegate_->OnBrowserChosen(browser_name);
 }
 
 }  // namespace win
 }  // namespace shell_integration