Allow FilePathWatcher to be used from sequenced tasks.

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 b9cd78aa3718dbf4951df8227df7aad54465ed9d..da587f4a6d2fd6eb32b701c092e4ba081276d464 100644
--- a/base/files/file_path_watcher.h
+++ b/base/files/file_path_watcher.h
@@ -13,7 +13,7 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequence_checker.h"
-#include "base/single_thread_task_runner.h"
+#include "base/sequenced_task_runner.h"
 
 namespace base {
 
@@ -56,11 +56,11 @@ class BASE_EXPORT FilePathWatcher {
 
     virtual ~PlatformDelegate();
 
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner() const {
+    scoped_refptr<SequencedTaskRunner> task_runner() const {
       return task_runner_;
     }
 
-    void set_task_runner(scoped_refptr<base::SingleThreadTaskRunner> runner) {
+    void set_task_runner(scoped_refptr<SequencedTaskRunner> runner) {
       task_runner_ = std::move(runner);
     }
 
@@ -74,7 +74,7 @@ class BASE_EXPORT FilePathWatcher {
     }
 
    private:
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+    scoped_refptr<SequencedTaskRunner> task_runner_;
     bool cancelled_;
   };