Add a non-blocking "OneShotEvent" class

chrome/browser/extensions/extension_system.cc

 // Copyright (c) 2012 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/extension_system.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 418 matching lines @@
 }
 
 ExtensionWarningService* ExtensionSystemImpl::warning_service() {
   return shared_->warning_service();
 }
 
 Blacklist* ExtensionSystemImpl::blacklist() {
   return shared_->blacklist();
 }
 
+const OneShotEvent& ExtensionSystemImpl::ready() const {
+  return *shared_->ready();
+}
+
+void ExtensionSystemImpl::ExtensionServiceReady() {
+  shared_->ready()->Signal();
+}
+
 void ExtensionSystemImpl::RegisterExtensionWithRequestContexts(
     const Extension* extension) {
   base::Time install_time;
   if (extension->location() != Manifest::COMPONENT) {
     install_time = extension_service()->extension_prefs()->
         GetInstallTime(extension->id());
   }
   bool incognito_enabled =
       extension_service()->IsIncognitoEnabled(extension->id());
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ExtensionInfoMap::AddExtension, info_map(),
                  make_scoped_refptr(extension), install_time,
                  incognito_enabled));
 }
 
 void ExtensionSystemImpl::UnregisterExtensionWithRequestContexts(
     const std::string& extension_id,
     const extension_misc::UnloadedExtensionReason reason) {
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ExtensionInfoMap::RemoveExtension, info_map(),
                  extension_id, reason));
 }
 
 }  // namespace extensions