Remove destruction observer from file_path_watcher_win.cc

base/files/file_path_watcher_win.cc

 // Copyright (c) 2011 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 "base/files/file_path_watcher.h"
 
 #include "base/bind.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/win/object_watcher.h"
 
 namespace base {
 
 namespace {
 
 class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate,
-                            public base::win::ObjectWatcher::Delegate,
-                            public MessageLoop::DestructionObserver {
+                            public base::win::ObjectWatcher::Delegate {
  public:
   FilePathWatcherImpl()
       : handle_(INVALID_HANDLE_VALUE),
         recursive_watch_(false) {}
 
-  // FilePathWatcher::PlatformDelegate overrides.
+  // FilePathWatcher::PlatformDelegate:
   bool Watch(const FilePath& path,
              bool recursive,
              const FilePathWatcher::Callback& callback) override;
   void Cancel() override;
 
-  // Deletion of the FilePathWatcher will call Cancel() to dispose of this
-  // object in the right thread. This also observes destruction of the required
-  // cleanup thread, in case it quits before Cancel() is called.
-  void WillDestroyCurrentMessageLoop() override;
-
-  // Callback from MessageLoopForIO.
+  // base::win::ObjectWatcher::Delegate:
   void OnObjectSignaled(HANDLE object) override;
 
  private:
   ~FilePathWatcherImpl() override {}
 
   // Setup a watch handle for directory |dir|. Set |recursive| to true to watch
   // the directory sub trees. Returns true if no fatal error occurs. |handle|
   // will receive the handle value if |dir| is watchable, otherwise
   // INVALID_HANDLE_VALUE.
   static bool SetupWatchHandle(const FilePath& dir,
                                bool recursive,
                                HANDLE* handle) WARN_UNUSED_RESULT;
 
   // (Re-)Initialize the watch handle.
   bool UpdateWatch() WARN_UNUSED_RESULT;
 
   // Destroy the watch handle.
   void DestroyWatch();
 
-  // Cleans up and stops observing the |task_runner_| thread.
-  void CancelOnMessageLoopThread();
-
   // Callback to notify upon changes.
   FilePathWatcher::Callback callback_;
 
   // Path we're supposed to watch (passed to callback).
   FilePath target_;
 
   // Handle for FindFirstChangeNotification.
   HANDLE handle_;
 
   // ObjectWatcher to watch handle_ for events.
@@ skipping 15 matching lines @@
 
 bool FilePathWatcherImpl::Watch(const FilePath& path,
                                 bool recursive,
                                 const FilePathWatcher::Callback& callback) {
   DCHECK(target_.value().empty());  // Can only watch one path.
 
   set_task_runner(ThreadTaskRunnerHandle::Get());
   callback_ = callback;
   target_ = path;
   recursive_watch_ = recursive;
-  MessageLoop::current()->AddDestructionObserver(this);
 
   File::Info file_info;
   if (GetFileInfo(target_, &file_info)) {
     last_modified_ = file_info.last_modified;
     first_notification_ = Time::Now();
   }
 
   if (!UpdateWatch())
     return false;
 
   watcher_.StartWatchingOnce(handle_, this);
 
   return true;
 }
 
 void FilePathWatcherImpl::Cancel() {
   if (callback_.is_null()) {
     // Watch was never called, or the |task_runner_| has already quit.
     set_cancelled();
     return;
   }
 
-  // Switch to the file thread if necessary so we can stop |watcher_|.
-  if (!task_runner()->BelongsToCurrentThread()) {
-    task_runner()->PostTask(
-        FROM_HERE, Bind(&FilePathWatcherImpl::CancelOnMessageLoopThread, this));
-  } else {
-    CancelOnMessageLoopThread();
-  }
-}
-
-void FilePathWatcherImpl::CancelOnMessageLoopThread() {
   DCHECK(task_runner()->BelongsToCurrentThread());
   set_cancelled();
 
   if (handle_ != INVALID_HANDLE_VALUE)
     DestroyWatch();
 
-  if (!callback_.is_null()) {
-    MessageLoop::current()->RemoveDestructionObserver(this);
-    callback_.Reset();
-  }
-}
-
-void FilePathWatcherImpl::WillDestroyCurrentMessageLoop() {
-  CancelOnMessageLoopThread();
+  callback_.Reset();
 }
 
 void FilePathWatcherImpl::OnObjectSignaled(HANDLE object) {
   DCHECK(object == handle_);
   // Make sure we stay alive through the body of this function.
   scoped_refptr<FilePathWatcherImpl> keep_alive(this);
 
   if (!UpdateWatch()) {
     callback_.Run(target_, true /* error */);
     return;
@@ skipping 137 matching lines @@
 }
 
 }  // namespace
 
 FilePathWatcher::FilePathWatcher() {
   sequence_checker_.DetachFromSequence();
   impl_ = new FilePathWatcherImpl();
 }
 
 }  // namespace base