Remove base::mac::LibDispatchTaskRunner and migrate its sole client to plain libdispatch.

base/files/file_path_watcher_fsevents.h

Index: base/files/file_path_watcher_fsevents.h
diff --git a/base/files/file_path_watcher_fsevents.h b/base/files/file_path_watcher_fsevents.h
index 1ebe4636e4ba19bfa58bc2eec84320ecd1720365..cfbe020b512cb26c4ab72d89a65d39e0f3d06660 100644
--- a/base/files/file_path_watcher_fsevents.h
+++ b/base/files/file_path_watcher_fsevents.h
@@ -12,6 +12,7 @@
 
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
+#include "base/mac/scoped_dispatch_object.h"
 #include "base/macros.h"
 
 namespace base {
@@ -76,16 +77,19 @@ class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate {
   // (Only accessed from the message_loop() thread.)
   FilePathWatcher::Callback callback_;
 
+  // The dispatch queue on which the the event stream is scheduled.
+  ScopedDispatchObject<dispatch_queue_t> queue_;
+
   // Target path to watch (passed to callback).
-  // (Only accessed from the libdispatch thread.)
+  // (Only accessed from the libdispatch queue.)
   FilePath target_;
 
   // Target path with all symbolic links resolved.
-  // (Only accessed from the libdispatch thread.)
+  // (Only accessed from the libdispatch queue.)
   FilePath resolved_target_;
 
   // Backend stream we receive event callbacks from (strong reference).
-  // (Only accessed from the libdispatch thread.)
+  // (Only accessed from the libdispatch queue.)
   FSEventStreamRef fsevent_stream_;
 
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcherFSEvents);