Migrate sync/ to base::RunLoop::RunUntilIdle()

sync/internal_api/attachments/fake_attachment_uploader_unittest.cc

Index: sync/internal_api/attachments/fake_attachment_uploader_unittest.cc
diff --git a/sync/internal_api/attachments/fake_attachment_uploader_unittest.cc b/sync/internal_api/attachments/fake_attachment_uploader_unittest.cc
index 45b4d303822d0cad2fccb5f9bb252aedfe87024f..5d86ad483b08299eb480443b64d7d52b14a96f61 100644
--- a/sync/internal_api/attachments/fake_attachment_uploader_unittest.cc
+++ b/sync/internal_api/attachments/fake_attachment_uploader_unittest.cc
@@ -7,7 +7,7 @@
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_memory.h"
-#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "sync/api/attachments/attachment.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -53,7 +53,7 @@ TEST_F(FakeAttachmentUploaderTest, UploadAttachment) {
   uploader.UploadAttachment(attachment1, upload_callback);
   uploader.UploadAttachment(attachment2, upload_callback);
   uploader.UploadAttachment(attachment3, upload_callback);
-  message_loop.RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
   EXPECT_EQ(upload_callback_count, 3);
 }