Remove FilePathWatcher::PlatformDelegate::CancelOnMessageLoopThread().

base/files/file_path_watcher.cc

Index: base/files/file_path_watcher.cc
diff --git a/base/files/file_path_watcher.cc b/base/files/file_path_watcher.cc
index a4624ab609aada2184d98681d8857fd5187c3cb6..e370fcb1355f0345238019cad8060b20f10b409f 100644
--- a/base/files/file_path_watcher.cc
+++ b/base/files/file_path_watcher.cc
@@ -18,12 +18,6 @@ FilePathWatcher::~FilePathWatcher() {
 }
 
 // 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) || \
     defined(OS_LINUX) || defined(OS_ANDROID)