https://bugs.webkit.org/show_bug.cgi?id=124043

Reviewed by Martin Robinson.

It happens because the print operation when started by the
WebProcess due to a DOM operation is supposed to be synchronous
and our print operation is always asynchronous. This is currently
handled only in the UI process because other ports print
synchronously in the WebProcess. In the GTK+ port we need to
notify the WebProcess that the print operation should run
synchronously when request by a DOM operation. Together with the
print settings and page setup we now send a print mode that can be
sync or async. When printing in sync mode we run a nested main loop
for the print operation, making sure that print sources have a
higher priority.

* Shared/PrintInfo.cpp:
(WebKit::PrintInfo::encode): Encode the print mode.
(WebKit::PrintInfo::decode): Decode the print mode.
* Shared/PrintInfo.h: Add PrintMode enum.
* Shared/gtk/PrintInfoGtk.cpp:
(WebKit::PrintInfo::PrintInfo): Initialize print mode.
* UIProcess/API/gtk/WebKitPrintOperation.cpp:
(drawPagesForPrintingCompleted): Do not call endPrinting() when
printing synchronously because WebPageProxy already calls it right
after sending the message to the WebProcess.
(webkitPrintOperationPrintPagesForFrame): Create the PrintInfo
struct with a print mode.
(webkitPrintOperationSetPrintMode): Helper private function to set
the print mode of the print operation.
* UIProcess/API/gtk/WebKitPrintOperationPrivate.h:
* UIProcess/API/gtk/WebKitWebView.cpp:
(webkitWebViewPrintFrame): Set sync print mode when printing due
to a UIClient request.
* WebProcess/WebPage/gtk/WebPrintOperationGtk.cpp:
(WebKit::PrintPagesData::PrintPagesData): Create a main loop when
printing synchronously.
(WebKit::WebPrintOperationGtk::WebPrintOperationGtk): Initialize
print mode.
(WebKit::WebPrintOperationGtk::printPagesIdleDone): Finish the
nested main loop when printing synchronously.
(WebKit::WebPrintOperationGtk::print): Run a nested main loop when
printing synchronously.
* WebProcess/WebPage/gtk/WebPrintOperationGtk.h:
(WebKit::WebPrintOperationGtk::printMode): Return the print mode.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@159042 268f45cc-cd09-0410-ab3c-d52691b4dbfc