Compile master, and run with `src/qt/bitcoin-qt -regtest -nowallet`. As expected, no icon is displayed. Load and unload a wallet. The `HD` icon remains.

On startup:
![on_startup](https://user-images.githubusercontent.com/863730/72410834-711b4c00-37a4-11ea-9a10-bfcf3db7ce68.png)

After a wallet load and unload:
![after_load_unload](https://user-images.githubusercontent.com/863730/72410838-737da600-37a4-11ea-8854-dd13301c0135.png)

switch (blockSource) {
        case BlockSource::NETWORK:
            if (header) {
                updateHeadersSyncProgressLabel();
                return;
            }
            progressBarLabel->setText(tr("Synchronizing with network..."));
            updateHeadersSyncProgressLabel();
            break;
        case BlockSource::DISK:
            if (header) {
                progressBarLabel->setText(tr("Indexing blocks on disk..."));
            } else {
                progressBarLabel->setText(tr("Processing blocks on disk..."));
            }
            break;
        case BlockSource::REINDEX:
            progressBarLabel->setText(tr("Reindexing blocks on disk..."));
            break;
        case BlockSource::NONE: