Prepare to migrate to QtWebEngine

CMakeLists.txt

@@ -82,6 +82,8 @@ option(KDEPIM_ENTERPRISE_BUILD "Enable features specific to the enterprise branc
 
 option(QTWEBENGINE_SUPPORT_OPTION "Enable support for QtWebEngine. False by default." FALSE)
 
+option(MESSAGEVIEWER_USE_QTWEBENGINE "Use QtWebEngine in mail viewer. False by default." FALSE)
+
 if (QTWEBENGINE_SUPPORT_OPTION)
     set(QT_REQUIRED_MINIMUM_WEBENGINE_VERSION "5.6")
     find_package(Qt5 ${QT_REQUIRED_MINIMUM_WEBENGINE_VERSION} CONFIG REQUIRED WebEngine WebEngineWidgets)

messageviewer/src/config-messageviewer.h.cmake

 #cmakedefine HAVE_SYS_INOTIFY_H 1
 
+#cmakedefine MESSAGEVIEWER_USE_QTWEBENGINE 1

messageviewer/src/viewer/viewer_p.h

@@ -22,6 +22,7 @@
 #define MAILVIEWER_P_H
 
 #include <MimeTreeParser/NodeHelper>
+#include "config-messageviewer.h"
 #include "viewer.h" //not so nice, it is actually for the enums from MailViewer
 #include "PimCommon/ShareServiceUrlManager"
 #include "messageviewer/viewerplugininterface.h"