Clean up threading model of external extension providers

chrome/browser/extensions/external_policy_extension_loader.cc

+// 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_policy_extension_loader.h"
+
+#include "base/logging.h"
+#include "base/values.h"
+#include "chrome/common/extensions/extension.h"
+#include "chrome/common/notification_service.h"
+#include "chrome/common/notification_type.h"
+#include "chrome/common/pref_names.h"
+#include "chrome/browser/browser_thread.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/profiles/profile.h"
+#include "googleurl/src/gurl.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;
+}
+
+}  // namespace
+
+ExternalPolicyExtensionLoader::ExternalPolicyExtensionLoader(
+    Profile* profile)
+    : profile_(profile) {
+  pref_change_registrar_.Init(profile_->GetPrefs());
+  pref_change_registrar_.Add(prefs::kExtensionInstallForceList, this);
+  notification_registrar_.Add(this,
+                              NotificationType::PROFILE_DESTROYED,
+                              Source<Profile>(profile_));
+}
+
+void ExternalPolicyExtensionLoader::StartLoading() {
+  const ListValue* forcelist =
+      profile_->GetPrefs()->GetList(prefs::kExtensionInstallForceList);
+  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);
+        }
+      }
+    }
+  }
+  prefs_.reset(result);
+  LoadFinished();
+}
+
+void ExternalPolicyExtensionLoader::Observe(
+    NotificationType type,
+    const NotificationSource& source,
+    const NotificationDetails& details) {
+  if (profile_ == NULL) return;
+  switch (type.value) {
+    case NotificationType::PREF_CHANGED: {
+      if (Source<PrefService>(source).ptr() == profile_->GetPrefs()) {
+        std::string* pref_name = Details<std::string>(details).ptr();
+        if (*pref_name == prefs::kExtensionInstallForceList) {
+          StartLoading();
+        } else {
+          NOTREACHED() << "Unexpected preference name.";
+        }
+      }
+      break;
+    }
+    case NotificationType::PROFILE_DESTROYED: {
+      if (Source<Profile>(source).ptr() == profile_) {
+        notification_registrar_.RemoveAll();
+        pref_change_registrar_.RemoveAll();
+        profile_ = NULL;
+      }
+      break;
+    }
+    default:
+      NOTREACHED() << "Unexpected notification type.";
+  }
+}