Revert of Require FilePathWatcher destructor to be called in sequence with Watch().

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 267c03ae00b7bb8600ade73b74236d3e68e12562..7b1483a404330c8844093aecc53b015fbc20cf40 100644
--- a/base/files/file_path_watcher.h
+++ b/base/files/file_path_watcher.h
@@ -12,7 +12,6 @@
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/sequence_checker.h"
 #include "base/single_thread_task_runner.h"
 
 namespace base {
@@ -26,8 +25,6 @@
 // detect the creation and deletion of files in a watched directory, but will
 // not detect modifications to those files. See file_path_watcher_kqueue.cc for
 // details.
-//
-// Must be destroyed on the sequence that invokes Watch().
 class BASE_EXPORT FilePathWatcher {
  public:
   // Callback type for Watch(). |path| points to the file that was updated,
@@ -79,7 +76,7 @@
   };
 
   FilePathWatcher();
-  ~FilePathWatcher();
+  virtual ~FilePathWatcher();
 
   // A callback that always cleans up the PlatformDelegate, either when executed
   // or when deleted without having been executed at all, as can happen during
@@ -101,8 +98,6 @@
  private:
   scoped_refptr<PlatformDelegate> impl_;
 
-  SequenceChecker sequence_checker_;
-
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcher);
 };