Clean up threading model of external extension providers

chrome/browser/extensions/external_extension_loader.cc

+// Copyright (c) 2010 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) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

[Aaron Boodman, 2011/01/06 18:54:40]

Don't be a wuss: s/DCHECK/CHECK/g

[gfeher, 2011/01/07 00:10:01]

Done.

+  owner_ = owner;
+}
+
+void ExternalExtensionLoader::StartLoading() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (running_) return;

[Aaron Boodman, 2011/01/06 18:54:40]

How would this ever get called twice?

[gfeher, 2011/01/07 00:10:01]

This can get called twice in case of ExternalPolicyExtensionLoader. But that
lives on the UI thread, so the two calls will never overlap.

I was trying to solve the problem when a loader is working on the FILE thread
and it is asked to start loading again. But this is not happening in the current
code. Whoever makes it happen will have more information to fix it the best way.

So I remove this check.

+  running_ = true;
+  Load();
+}
+
+void ExternalExtensionLoader::OwnerShutdown() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  owner_ = NULL;
+}
+
+void ExternalExtensionLoader::LoadFinished() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  running_ = false;
+  if (owner_) {
+    AutoLock auto_(lock_);
+    owner_->SetPrefs(prefs_.release());
+  }
+}