Fix windows registry loader to carry over prefs from file thread correctly

chrome/browser/extensions/external_registry_loader_win.cc

Index: chrome/browser/extensions/external_registry_loader_win.cc
diff --git a/chrome/browser/extensions/external_registry_loader_win.cc b/chrome/browser/extensions/external_registry_loader_win.cc
index 0c1088480c2f2fc7d76b71ff0e094b469b24a53e..6f331080d34cf8a44a471ea63bb44eae9eb68c81 100644
--- a/chrome/browser/extensions/external_registry_loader_win.cc
+++ b/chrome/browser/extensions/external_registry_loader_win.cc
@@ -190,17 +190,20 @@ ExternalRegistryLoader::LoadPrefsOnFileThread() {
 
 void ExternalRegistryLoader::LoadOnFileThread() {
   base::TimeTicks start_time = base::TimeTicks::Now();
-  prefs_ = LoadPrefsOnFileThread();
+  std::unique_ptr<base::DictionaryValue> prefs = LoadPrefsOnFileThread();
   LOCAL_HISTOGRAM_TIMES("Extensions.ExternalRegistryLoaderWin",
                         base::TimeTicks::Now() - start_time);
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&ExternalRegistryLoader::CompleteLoadAndStartWatchingRegistry,
-                 this));
+                 this, base::Passed(&prefs)));
 }
 
-void ExternalRegistryLoader::CompleteLoadAndStartWatchingRegistry() {
+void ExternalRegistryLoader::CompleteLoadAndStartWatchingRegistry(
+    std::unique_ptr<base::DictionaryValue> prefs) {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(prefs);
+  prefs_ = std::move(prefs);
   LoadFinished();
 
   // Attempt to watch registry if we haven't already.