Mirror syncfs log to console and WebUI, with LogSeverity support.

chrome/browser/sync_file_system/local_file_sync_service.cc

Index: chrome/browser/sync_file_system/local_file_sync_service.cc
diff --git a/chrome/browser/sync_file_system/local_file_sync_service.cc b/chrome/browser/sync_file_system/local_file_sync_service.cc
index 671daebdaec70835462419d0f9af23c29c7c6b1e..7b5d26fa5b5a28a2b64eaa671927578b6ac90d6f 100644
--- a/chrome/browser/sync_file_system/local_file_sync_service.cc
+++ b/chrome/browser/sync_file_system/local_file_sync_service.cc
@@ -9,6 +9,7 @@
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sync_file_system/local_change_processor.h"
+#include "chrome/browser/sync_file_system/logger.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/site_instance.h"
@@ -200,8 +201,11 @@ void LocalFileSyncService::PrepareForProcessRemoteChange(
     const extensions::Extension* extension = extension_service->GetInstalledApp(
         url.origin());
     if (!extension) {
-      LOG(WARNING) << "PrepareForProcessRemoteChange called for non-existing "
-                   << " origin:" << url.origin().spec();
+      SYNCFS_LOG(
+          WARNING,
+          "PrepareForProcessRemoteChange called for non-existing origin: %s",
+          url.origin().spec().c_str());
+
       // The extension has been uninstalled and this method is called
       // before the remote changes for the origin are removed.
       callback.Run(SYNC_STATUS_NO_CHANGE_TO_SYNC,