Fix potential deadlock between AudioPolicyService and AudioSystem

        }

        binder->linkToDeath(gAudioPolicyServiceClient);

        gAudioPolicyService = interface_cast<IAudioPolicyService>(binder);

        gAudioPolicyService->registerClient(gAudioPolicyServiceClient);

        gLock.unlock();

        // Registering the client takes the AudioPolicyService lock.

        // Don't hold the AudioSystem lock at the same time.

        gAudioPolicyService->registerClient(gAudioPolicyServiceClient);

    } else {

        // There exists a benign race condition where gAudioPolicyService

        // is set, but gAudioPolicyServiceClient is not yet registered.

        gLock.unlock();

    }

    return gAudioPolicyService;