Remove base::Value::CreateNullValue

chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc

Index: chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc
diff --git a/chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc b/chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc
index 40b22eadf7a88539ac7c40a2083e4735fa6ab6a0..fbf927a4f782890dd000c1a8ee4ad26ffff58fbe 100644
--- a/chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc
+++ b/chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc
@@ -336,7 +336,7 @@ bool FileManagerPrivateRequestWebStoreAccessTokenFunction::RunAsync() {
                   "CWS OAuth token fetch failed. OAuth2TokenService can't "
                   "be retrieved.");
     }
-    SetResult(base::Value::CreateNullValue());
+    SetResult(base::MakeUnique<base::Value>());
     return false;
   }
 
@@ -373,7 +373,7 @@ void FileManagerPrivateRequestWebStoreAccessTokenFunction::OnAccessTokenFetched(
                   "CWS OAuth token fetch failed. (DriveApiErrorCode: %s)",
                   google_apis::DriveApiErrorCodeToString(code).c_str());
     }
-    SetResult(base::Value::CreateNullValue());
+    SetResult(base::MakeUnique<base::Value>());
     SendResponse(false);
   }
 }