Remove FilePathWatcher::PlatformDelegate::CancelOnMessageLoopThread().

There is no reason to have this method in the PlatformDelegate
interface it can simply be declared in subclasses that need it.

BUG=650318

Review-Url: https://codereview.chromium.org/2372513005
Cr-Commit-Position: refs/heads/master@{#421583}

base/files/file_path_watcher.cc

@@ -17,12 +17,6 @@ FilePathWatcher::~FilePathWatcher() {
   impl_->Cancel();
 }
 
-// static
-void FilePathWatcher::CancelWatch(
-    const scoped_refptr<PlatformDelegate>& delegate) {
-  delegate->CancelOnMessageLoopThread();
-}
-
 // static
 bool FilePathWatcher::RecursiveWatchAvailable() {
 #if (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_WIN) || \

base/files/file_path_watcher.h

@@ -53,11 +53,6 @@ class BASE_EXPORT FilePathWatcher {
 
     virtual ~PlatformDelegate();
 
-    // Stop watching. This is only called on the thread of the appropriate
-    // message loop. Since it can also be called more than once, it should
-    // check |is_cancelled()| to avoid duplicate work.
-    virtual void CancelOnMessageLoopThread() = 0;
-
     scoped_refptr<base::SingleThreadTaskRunner> task_runner() const {
       return task_runner_;
     }

base/files/file_path_watcher_fsevents.h

@@ -54,7 +54,7 @@ class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate {
                       const FilePath& resolved_target);
 
   // Cleans up and stops the event stream.
-  void CancelOnMessageLoopThread() override;
+  void CancelOnMessageLoopThread();
 
   // (Re-)Initialize the event stream to start reporting events from
   // |start_event|.

base/files/file_path_watcher_kqueue.h

@@ -61,7 +61,7 @@ class FilePathWatcherKQueue : public FilePathWatcher::PlatformDelegate,
   typedef std::vector<struct kevent> EventVector;
 
   // Can only be called on |io_task_runner_|'s thread.
-  void CancelOnMessageLoopThread() override;
+  void CancelOnMessageLoopThread();
 
   // Returns true if the kevent values are error free.
   bool AreKeventValuesValid(struct kevent* kevents, int count);

base/files/file_path_watcher_linux.cc

@@ -120,7 +120,6 @@ class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate {
 
   // Cancel the watch. This unregisters the instance with InotifyReader.
   void Cancel() override;
-  void CancelOnMessageLoopThread() override;
   void CancelOnMessageLoopThreadOrInDestructor();
 
   // Inotify watches are installed for all directory components of |target_|.
@@ -329,8 +328,8 @@ void FilePathWatcherImpl::OnFilePathChanged(InotifyReader::Watch fired_watch,
     return;
   }
 
-  // Check to see if CancelOnMessageLoopThread() has already been called.
-  // May happen when code flow reaches here from the PostTask() above.
+  // Check to see if CancelOnMessageLoopThreadOrInDestructor() has already been
+  // called. May happen when code flow reaches here from the PostTask() above.
   if (watches_.empty()) {
     DCHECK(target_.empty());
     return;
@@ -445,19 +444,17 @@ void FilePathWatcherImpl::Cancel() {
     return;
   }
 
-  // Switch to the message_loop() if necessary so we can access |watches_|.
+  // Switch to the task_runner() if necessary so we can access |watches_|.
   if (!task_runner()->BelongsToCurrentThread()) {
-    task_runner()->PostTask(FROM_HERE, Bind(&FilePathWatcher::CancelWatch,
-                                            make_scoped_refptr(this)));
+    task_runner()->PostTask(
+        FROM_HERE,
+        Bind(&FilePathWatcherImpl::CancelOnMessageLoopThreadOrInDestructor,
+             this));
   } else {
-    CancelOnMessageLoopThread();
+    CancelOnMessageLoopThreadOrInDestructor();
   }
 }
 
-void FilePathWatcherImpl::CancelOnMessageLoopThread() {
-  CancelOnMessageLoopThreadOrInDestructor();
-}
-
 void FilePathWatcherImpl::CancelOnMessageLoopThreadOrInDestructor() {
   DCHECK(in_destructor_ || task_runner()->BelongsToCurrentThread());
 
@@ -479,7 +476,7 @@ void FilePathWatcherImpl::CancelOnMessageLoopThreadOrInDestructor() {
 }
 
 void FilePathWatcherImpl::UpdateWatches() {
-  // Ensure this runs on the message_loop() exclusively in order to avoid
+  // Ensure this runs on the task_runner() exclusively in order to avoid
   // concurrency issues.
   DCHECK(task_runner()->BelongsToCurrentThread());
   DCHECK(HasValidWatchVector());

base/files/file_path_watcher_mac.cc

@@ -40,12 +40,6 @@ class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate {
     set_cancelled();
   }
 
-  void CancelOnMessageLoopThread() override {
-    if (impl_.get())
-      impl_->Cancel();
-    set_cancelled();
-  }
-
  protected:
   ~FilePathWatcherImpl() override {}
 

base/files/file_path_watcher_stub.cc

@@ -21,8 +21,6 @@ class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate {
 
   void Cancel() override {}
 
-  void CancelOnMessageLoopThread() override {}
-
  protected:
   ~FilePathWatcherImpl() override {}
 };

base/files/file_path_watcher_win.cc

@@ -60,7 +60,7 @@ class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate,
   void DestroyWatch();
 
   // Cleans up and stops observing the |task_runner_| thread.
-  void CancelOnMessageLoopThread() override;
+  void CancelOnMessageLoopThread();
 
   // Callback to notify upon changes.
   FilePathWatcher::Callback callback_;
@@ -122,8 +122,8 @@ void FilePathWatcherImpl::Cancel() {
 
   // Switch to the file thread if necessary so we can stop |watcher_|.
   if (!task_runner()->BelongsToCurrentThread()) {
-    task_runner()->PostTask(FROM_HERE, Bind(&FilePathWatcher::CancelWatch,
-                                            make_scoped_refptr(this)));
+    task_runner()->PostTask(
+        FROM_HERE, Bind(&FilePathWatcherImpl::CancelOnMessageLoopThread, this));
   } else {
     CancelOnMessageLoopThread();
   }