Eliminate FilePathWatcher::Delegate.

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/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop_proxy.h"
 #include "base/time.h"
 #include "base/win/object_watcher.h"
 
 namespace base {
 namespace files {
 
 namespace {
 
 class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate,
                             public base::win::ObjectWatcher::Delegate,
                             public MessageLoop::DestructionObserver {
  public:
   FilePathWatcherImpl()
-      : delegate_(NULL),
-        handle_(INVALID_HANDLE_VALUE),
+      : handle_(INVALID_HANDLE_VALUE),
         recursive_watch_(false) {}
 
   // FilePathWatcher::PlatformDelegate overrides.
   virtual bool Watch(const FilePath& path,
                      bool recursive,
-                     FilePathWatcher::Delegate* delegate) OVERRIDE;
+                     const FilePathWatcher::Callback& callback) OVERRIDE;
   virtual 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.
   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
 
   // Callback from MessageLoopForIO.
   virtual void OnObjectSignaled(HANDLE object);
 
@@ skipping 10 matching lines @@
 
   // (Re-)Initialize the watch handle.
   bool UpdateWatch() WARN_UNUSED_RESULT;
 
   // Destroy the watch handle.
   void DestroyWatch();
 
   // Cleans up and stops observing the |message_loop_| thread.
   void CancelOnMessageLoopThread() OVERRIDE;
 
-  // Delegate to notify upon changes.
-  scoped_refptr<FilePathWatcher::Delegate> delegate_;
+  // Callback to notify upon changes.
+  FilePathWatcher::Callback callback_;
 
-  // Path we're supposed to watch (passed to delegate).
+  // Path we're supposed to watch (passed to callback).
   FilePath target_;
 
   // Handle for FindFirstChangeNotification.
   HANDLE handle_;
 
   // ObjectWatcher to watch handle_ for events.
   base::win::ObjectWatcher watcher_;
 
   // Set to true to watch the sub trees of the specified directory file path.
   bool recursive_watch_;
 
   // Keep track of the last modified time of the file.  We use nulltime
   // to represent the file not existing.
   base::Time last_modified_;
 
   // The time at which we processed the first notification with the
   // |last_modified_| time stamp.
   base::Time first_notification_;
 
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcherImpl);
 };
 
 bool FilePathWatcherImpl::Watch(const FilePath& path,
                                 bool recursive,
-                                FilePathWatcher::Delegate* delegate) {
+                                const FilePathWatcher::Callback& callback) {
   DCHECK(target_.value().empty());  // Can only watch one path.
 
   set_message_loop(base::MessageLoopProxy::current());
-  delegate_ = delegate;
+  callback_ = callback;
   target_ = path;
   recursive_watch_ = recursive;
   MessageLoop::current()->AddDestructionObserver(this);
 
   if (!UpdateWatch())
     return false;
 
   watcher_.StartWatching(handle_, this);
 
   return true;
 }
 
 void FilePathWatcherImpl::Cancel() {
-  if (!delegate_) {
+  if (callback_.is_null()) {
     // Watch was never called, or the |message_loop_| has already quit.
     set_cancelled();
     return;
   }
 
   // Switch to the file thread if necessary so we can stop |watcher_|.
   if (!message_loop()->BelongsToCurrentThread()) {
     message_loop()->PostTask(FROM_HERE,
                              base::Bind(&FilePathWatcher::CancelWatch,
                                         make_scoped_refptr(this)));
   } else {
     CancelOnMessageLoopThread();
   }
 }
 
 void FilePathWatcherImpl::CancelOnMessageLoopThread() {
   set_cancelled();
 
   if (handle_ != INVALID_HANDLE_VALUE)
     DestroyWatch();
 
-  if (delegate_) {
+  if (!callback_.is_null()) {
     MessageLoop::current()->RemoveDestructionObserver(this);
-    delegate_ = NULL;
+    callback_.Reset();
   }
 }
 
 void FilePathWatcherImpl::WillDestroyCurrentMessageLoop() {
   CancelOnMessageLoopThread();
 }
 
 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()) {
-    delegate_->OnFilePathError(target_);
+    callback_.Run(target_, true /* error */);
     return;
   }
 
-  // Check whether the event applies to |target_| and notify the delegate.
+  // Check whether the event applies to |target_| and notify the callback.
   base::PlatformFileInfo file_info;
   bool file_exists = file_util::GetFileInfo(target_, &file_info);
   if (file_exists && (last_modified_.is_null() ||
       last_modified_ != file_info.last_modified)) {
     last_modified_ = file_info.last_modified;
     first_notification_ = base::Time::Now();
-    delegate_->OnFilePathChanged(target_);
+    callback_.Run(target_, false);
   } else if (file_exists && !first_notification_.is_null()) {
     // The target's last modification time is equal to what's on record. This
     // means that either an unrelated event occurred, or the target changed
     // again (file modification times only have a resolution of 1s). Comparing
     // file modification times against the wall clock is not reliable to find
     // out whether the change is recent, since this code might just run too
     // late. Moreover, there's no guarantee that file modification time and wall
     // clock times come from the same source.
     //
     // Instead, the time at which the first notification carrying the current
     // |last_notified_| time stamp is recorded. Later notifications that find
     // the same file modification time only need to be forwarded until wall
     // clock has advanced one second from the initial notification. After that
     // interval, client code is guaranteed to having seen the current revision
     // of the file.
     if (base::Time::Now() - first_notification_ >
         base::TimeDelta::FromSeconds(1)) {
       // Stop further notifications for this |last_modification_| time stamp.
       first_notification_ = base::Time();
     }
-    delegate_->OnFilePathChanged(target_);
+    callback_.Run(target_, false);
   } else if (!file_exists && !last_modified_.is_null()) {
     last_modified_ = base::Time();
-    delegate_->OnFilePathChanged(target_);
+    callback_.Run(target_, false);
   }
 
   // The watch may have been cancelled by the callback.
   if (handle_ != INVALID_HANDLE_VALUE)
     watcher_.StartWatching(handle_, this);
 }
 
 // static
 bool FilePathWatcherImpl::SetupWatchHandle(const FilePath& dir,
                                            bool recursive,
@@ skipping 92 matching lines @@
 }
 
 }  // namespace
 
 FilePathWatcher::FilePathWatcher() {
   impl_ = new FilePathWatcherImpl();
 }
 
 }  // namespace files
 }  // namespace base