Eliminate CHECK from CryptohomeLibrary::LoadSystemSalt

chrome/browser/extensions/api/music_manager_private/device_id_chromeos.cc

 // Copyright 2013 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/api/music_manager_private/device_id.h"
 
+#include "base/message_loop/message_loop.h"
 #include "chromeos/cryptohome/cryptohome_library.h"
 
 namespace extensions {
 namespace api {
 
 // ChromeOS: Use the System Salt.
 /* static */
 void DeviceId::GetMachineId(const IdCallback& callback) {
   chromeos::CryptohomeLibrary* c_home = chromeos::CryptohomeLibrary::Get();
   std::string result = c_home->GetSystemSalt();
+  if (result.empty()) {
+    // cryptohome must not be running; re-request after a delay.
+    const int64 kRequestStstemSaltDelayMs = 500;
+    base::MessageLoop::current()->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&DeviceId::GetMachineId, callback),
+        base::TimeDelta::FromMilliseconds(kRequestStstemSaltDelayMs));
+    return;
+  }
   callback.Run(result);
 }
 
 }  // namespace api
 }  // namespace extensions