Clean up threading model of external extension providers

chrome/browser/extensions/external_extension_loader.cc

Index: chrome/browser/extensions/external_extension_loader.cc
diff --git a/chrome/browser/extensions/external_extension_loader.cc b/chrome/browser/extensions/external_extension_loader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..79fc78795315f82afd51a7b9e498420d86896cb6
--- /dev/null
+++ b/chrome/browser/extensions/external_extension_loader.cc
@@ -0,0 +1,29 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/extensions/external_extension_loader.h"
+
+#include "base/logging.h"
+#include "base/values.h"
+#include "chrome/browser/browser_thread.h"
+#include "chrome/browser/extensions/external_extension_provider_impl.h"
+
+void ExternalExtensionLoader::Init(
+    ExternalExtensionProviderImpl* owner) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  owner_ = owner;
+}
+
+void ExternalExtensionLoader::OwnerShutdown() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  owner_ = NULL;
+}
+
+void ExternalExtensionLoader::LoadFinished() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  running_ = false;
+  if (owner_) {
+    owner_->SetPrefs(prefs_.release());
+  }
+}