Clean up threading model of external extension providers

Move blocking IO of loading the lists of external extensions from the UI thread to the FILE thread. Remove the ExternalPolicyExtensionProvider-specific parts from ExtensionsService. Side-effects: reduce the number of PostTask operations from 9 to 4. Trigger uninstall of external extensions immediately after they are removed from a policy.

BUG=65107,63667
TEST=ExtensionManagementTest.ExternalPolicyRefresh for the new functionality, lot of other extension tests are updated

Review URL: http://codereview.chromium.org/5742008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@71427 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 28 insertions, 0 deletions

diff --git a/chrome/browser/extensions/external_registry_extension_loader_win.h b/chrome/browser/extensions/external_registry_extension_loader_win.h
new file mode 100644
index 0000000..7b0d189
--- /dev/null
+++ b/chrome/browser/extensions/external_registry_extension_loader_win.h
@@ -0,0 +1,28 @@
+// 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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTERNAL_REGISTRY_EXTENSION_LOADER_WIN_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTERNAL_REGISTRY_EXTENSION_LOADER_WIN_H_
+#pragma once
+
+#include "chrome/browser/extensions/external_extension_loader.h"
+
+class ExternalRegistryExtensionLoader : public ExternalExtensionLoader {
+ public:
+  ExternalRegistryExtensionLoader() {}
+
+ protected:
+  virtual void StartLoading();
+
+ private:
+  friend class base::RefCountedThreadSafe<ExternalExtensionLoader>;
+
+  virtual ~ExternalRegistryExtensionLoader() {}
+
+  void LoadOnFileThread();
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalRegistryExtensionLoader);
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_REGISTRY_EXTENSION_LOADER_WIN_H_