base: Remove most uses of MessageLoopProxy

Replace most usage of MessageLoopProxy under base/ with SingleThreadTaskRunner
and ThreadTaskRunnerHandle (excluding the implementation of MessageLoopProxy
itself which will removed later).

This patch was mostly autogenerated with
https://codereview.chromium.org/1010073002.

Depends on https://codereview.chromium.org/1086733002/.

BUG=465354
TBR=nkostylev@chromium.org,pkasting@chromium.org,pauljensen@chromium.org

Review URL: https://codereview.chromium.org/1100773004

Cr-Commit-Position: refs/heads/master@{#327755}


CrOS-Libchrome-Original-Commit: 054861d0934c663de3cea933e1d65fd8319856a6
diff --git a/base/files/file_path_watcher.h b/base/files/file_path_watcher.h
index d26fa06..4f132af 100644
--- a/base/files/file_path_watcher.h
+++ b/base/files/file_path_watcher.h
@@ -12,7 +12,7 @@
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop_proxy.h"
+#include "base/single_thread_task_runner.h"
 
 namespace base {
 
@@ -58,12 +58,13 @@
     // check |is_cancelled()| to avoid duplicate work.
     virtual void CancelOnMessageLoopThread() = 0;
 
-    scoped_refptr<base::MessageLoopProxy> message_loop() const {
-      return message_loop_;
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner() const {
+      return task_runner_;
     }
 
-    void set_message_loop(const scoped_refptr<base::MessageLoopProxy>& loop) {
-      message_loop_ = loop;
+    void set_task_runner(
+        scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+      task_runner_ = task_runner.Pass();
     }
 
     // Must be called before the PlatformDelegate is deleted.
@@ -76,7 +77,7 @@
     }
 
    private:
-    scoped_refptr<base::MessageLoopProxy> message_loop_;
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
     bool cancelled_;
   };