Remove unused ThreadSafeAskFee from ui_interface

ThreadSafeAskFee is effectively unused. It is only called
when the fAskFee parameter on SendMoney or SendMoneyToDestination
is true, which never happens. Remove it.

src/qt/bitcoin.cpp

@@ -74,22 +74,6 @@ static bool ThreadSafeMessageBox(const std::string& message, const std::string&
     }
 }
 
-static bool ThreadSafeAskFee(int64_t nFeeRequired)
-{
-    if(!guiref)
-        return false;
-    if(nFeeRequired < CTransaction::nMinTxFee || nFeeRequired <= nTransactionFee || fDaemon)
-        return true;
-
-    bool payFee = false;
-
-    QMetaObject::invokeMethod(guiref, "askFee", GUIUtil::blockingGUIThreadConnection(),
-                               Q_ARG(qint64, nFeeRequired),
-                               Q_ARG(bool*, &payFee));
-
-    return payFee;
-}
-
 static void InitMessage(const std::string &message)
 {
     if(splashref)
@@ -262,7 +246,6 @@ int main(int argc, char *argv[])
 
     // Subscribe to global signals from core
     uiInterface.ThreadSafeMessageBox.connect(ThreadSafeMessageBox);
-    uiInterface.ThreadSafeAskFee.connect(ThreadSafeAskFee);
     uiInterface.InitMessage.connect(InitMessage);
     uiInterface.Translate.connect(Translate);
 

src/qt/bitcoingui.cpp

@@ -726,19 +726,6 @@ void BitcoinGUI::closeEvent(QCloseEvent *event)
     QMainWindow::closeEvent(event);
 }
 
-void BitcoinGUI::askFee(qint64 nFeeRequired, bool *payFee)
-{
-    if (!clientModel || !clientModel->getOptionsModel())
-        return;
-
-    QString strMessage = tr("This transaction is over the size limit. You can still send it for a fee of %1, "
-        "which goes to the nodes that process your transaction and helps to support the network. "
-        "Do you want to pay the fee?").arg(BitcoinUnits::formatWithUnit(clientModel->getOptionsModel()->getDisplayUnit(), nFeeRequired));
-    QMessageBox::StandardButton retval = QMessageBox::question(this, tr("Confirm transaction fee"), strMessage,
-        QMessageBox::Yes | QMessageBox::Cancel, QMessageBox::Yes);
-    *payFee = (retval == QMessageBox::Yes);
-}
-
 void BitcoinGUI::incomingTransaction(const QString& date, int unit, qint64 amount, const QString& type, const QString& address)
 {
     // On new transaction, make an info balloon

src/qt/bitcoingui.h

@@ -135,16 +135,6 @@ public slots:
     */
     void message(const QString &title, const QString &message, unsigned int style, bool *ret = NULL);
 
-    /** Asks the user whether to pay the transaction fee or to cancel the transaction.
-       It is currently not possible to pass a return value to another thread through
-       BlockingQueuedConnection, so an indirected pointer is used.
-       https://bugreports.qt-project.org/browse/QTBUG-10440
-
-      @param[in] nFeeRequired       the required fee
-      @param[out] payFee            true to pay the fee, false to not pay the fee
-    */
-    void askFee(qint64 nFeeRequired, bool *payFee);
-
     bool handlePaymentRequest(const SendCoinsRecipient& recipient);
 
     /** Show incoming transaction notification for new transactions. */