Fix CFWL_WidgetImpDelegate hierarchy.

Fix CFWL_WidgetImpDelegate hierarchy.

Instead of casting to the unrelated IFWL_WidgetDelegate class
and hoping that its vtables line up, make CFWL_WidgetImpDelegate
inherit from it. We can then remove a lot of casting, even during
delete given that it has a virtual dtor.

R=thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/a4754b4d4ebc5e518a1d1363648042a5c7add544

[Tom Sepez, 2015-11-19 18:54:06]

Lei, for review.  The finalize is pointless and should be performed by a dtor,
but leave it for now.

[Tom Sepez, 2015-11-19 20:19:43]

Description was changed from

==========
Fix CFWL_WidgetImpDelegate hierarchy.

Instead of casting to the unrelated IFWL_WidgetDelegate class
and hoping that its vtables line up, make CFWL_WidgetImpDelegate
inherit from it. We can then remove a lot of casting, even during
delete given that it has a virtual dtor.
==========

to

==========
Fix CFWL_WidgetImpDelegate hierarchy.

Instead of casting to the unrelated IFWL_WidgetDelegate class
and hoping that its vtables line up, make CFWL_WidgetImpDelegate
inherit from it. We can then remove a lot of casting, even during
delete given that it has a virtual dtor.
==========

[Tom Sepez, 2015-11-19 20:19:43]

tsepez@chromium.org changed reviewers:
+ thestig@chromium.org

[Tom Sepez, 2015-11-19 20:19:56]

Actually adding reviewer.

[Lei Zhang, 2015-11-20 03:11:43]

lgtm

https://codereview.chromium.org/1458173002/diff/1/xfa/src/fwl/src/basewidget/...
File xfa/src/fwl/src/basewidget/fwl_barcodeimp.cpp (left):

https://codereview.chromium.org/1458173002/diff/1/xfa/src/fwl/src/basewidget/...
xfa/src/fwl/src/basewidget/fwl_barcodeimp.cpp:54: m_pDelegate =
(IFWL_WidgetDelegate*)new CFWL_BarcodeImpDelegate(this);
Ya, umm, wow.

[Tom Sepez, 2015-11-20 18:35:10]

Committed patchset #1 (id:1) manually as
a4754b4d4ebc5e518a1d1363648042a5c7add544 (presubmit successful).