tdf#115218 framework: decouple HiddenForConversion from Hidden

Commit 4a0f506f (framework: disable
layout manager in hidden frames, 2018-01-17) added support for bypassing
the framework layout manager for doc conversion purposes, but the Hidden
flag has the meaning that the doc is only initially hidden, it may be
visible later, so reusing Hidden broke mail merge.

Introduce a dedicated HiddenForConversion flag, clients interested in
improved performance can opt in for that, and this way behavior for
Hidden is not changing.

Change-Id: If7537197900f8819f714b164c9e056b4ae69286d
Reviewed-on: https://gerrit.libreoffice.org/49302Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

framework/source/classes/taskcreator.cxx

@@ -110,8 +110,8 @@ css::uno::Reference< css::frame::XFrame > TaskCreator::createTask( const OUStrin
     lArgs[4]   <<= aArg;
 
     bool bHidden
-        = rDescriptor.getUnpackedValueOrDefault(utl::MediaDescriptor::PROP_HIDDEN(), false);
-    aArg.Name = "Hidden";
+        = rDescriptor.getUnpackedValueOrDefault("HiddenForConversion", false);
+    aArg.Name = "HiddenForConversion";
     aArg.Value <<= bHidden;
     lArgs[5] <<= aArg;
 

framework/source/services/taskcreatorsrv.cxx

@@ -130,7 +130,7 @@ css::uno::Reference< css::uno::XInterface > SAL_CALL TaskCreatorService::createI
     bool                                  bSupportPersistentWindowState = lArgs.getUnpackedValueOrDefault(ARGUMENT_SUPPORTPERSISTENTWINDOWSTATE , false );
     bool                                  bEnableTitleBarUpdate         = lArgs.getUnpackedValueOrDefault(ARGUMENT_ENABLE_TITLEBARUPDATE        , true );
     // If the frame is explicitly requested to be hidden.
-    bool bHidden = lArgs.getUnpackedValueOrDefault("Hidden", false);
+    bool bHidden = lArgs.getUnpackedValueOrDefault("HiddenForConversion", false);
 
     // We use FrameName property to set it as API name of the new created frame later.
     // But those frame names must be different from the set of special target names as e.g. _blank, _self etcpp !