Clean up threading model of external extension providers

chrome/browser/extensions/external_policy_extension_provider.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_policy_extension_provider.h"
-
-#include "base/logging.h"
-#include "base/values.h"
-#include "chrome/common/pref_names.h"
-#include "chrome/browser/browser_thread.h"
-#include "chrome/browser/extensions/stateful_external_extension_provider.h"
-#include "chrome/browser/prefs/pref_service.h"
-
-namespace {
-
-// Check an extension ID and an URL to be syntactically correct.
-bool CheckExtension(std::string id, std::string update_url) {
-  GURL url(update_url);
-  if (!url.is_valid()) {
-    LOG(WARNING) << "Policy specifies invalid update URL for external "
-                 << "extension: " << update_url;
-    return false;
-  }
-  if (!Extension::IdIsValid(id)) {
-    LOG(WARNING) << "Policy specifies invalid ID for external "
-                 << "extension: " << id;
-    return false;
-  }
-  return true;
-}
-
-}
-
-ExternalPolicyExtensionProvider::ExternalPolicyExtensionProvider(
-    const ListValue* forcelist)
-        : StatefulExternalExtensionProvider(
-            Extension::INVALID,
-            Extension::EXTERNAL_POLICY_DOWNLOAD) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  ProcessPreferences(forcelist);
-}
-
-ExternalPolicyExtensionProvider::~ExternalPolicyExtensionProvider() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-}
-
-void ExternalPolicyExtensionProvider::SetPreferences(
-    const ListValue* forcelist) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  ProcessPreferences(forcelist);
-}
-
-void ExternalPolicyExtensionProvider::ProcessPreferences(
-    const ListValue* forcelist) {
-  DictionaryValue* result = new DictionaryValue();
-  if (forcelist != NULL) {
-    std::string extension_desc;
-    for (ListValue::const_iterator it = forcelist->begin();
-         it != forcelist->end(); ++it) {
-      if (!(*it)->GetAsString(&extension_desc)) {
-        LOG(WARNING) << "Failed to read forcelist string.";
-      } else {
-        // Each string item of the list has the following form:
-        // extension_id_code;extension_update_url
-        // The update URL might also contain semicolons.
-        size_t pos = extension_desc.find(';');
-        std::string id = extension_desc.substr(0, pos);
-        std::string update_url = extension_desc.substr(pos+1);
-        if (CheckExtension(id, update_url)) {
-          result->SetString(id + ".external_update_url", update_url);
-        }
-      }
-    }
-  }
-  set_prefs(result);
-}