Remove FilePathWatcher::PlatformDelegate::CancelOnMessageLoopThread().

base/files/file_path_watcher.h

Index: base/files/file_path_watcher.h
diff --git a/base/files/file_path_watcher.h b/base/files/file_path_watcher.h
index d5c6db1acfe74f1d30b7ea7f96c838067b092641..7b1483a404330c8844093aecc53b015fbc20cf40 100644
--- a/base/files/file_path_watcher.h
+++ b/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_;
     }