Make code compile with clang_use_chrome_plugin (part VI)

This change mainly contains files in xfa/fwl directory.
This is part of the efforts to make PDFium code compilable
by Clang chromium style plugins.

The changes are mainly the following:
-- move inline constructor/destructor of complex class/struct out-of-line;
-- add constructor/destructor of complex class/struct if not
 explicitly defined;
-- add explicit out-of-line copy constructor when needed;
-- move inline virtual functions out-of-line;
-- Properly mark virtual functions with 'override';
-- some minor cleanups;

BUG=pdfium:469

Review-Url: https://codereview.chromium.org/2070583003

1 files changed, 12 insertions, 0 deletions

diff --git a/xfa/fwl/lightwidget/cfwl_listbox.cpp b/xfa/fwl/lightwidget/cfwl_listbox.cpp
index d51db44f3b..be6a6b1249 100644
--- a/xfa/fwl/lightwidget/cfwl_listbox.cpp
+++ b/xfa/fwl/lightwidget/cfwl_listbox.cpp
@@ -341,3 +341,15 @@ FWL_Error CFWL_ListBox::CFWL_ListBoxDP::SetItemCheckState(
   static_cast<CFWL_ListItem*>(pItem)->m_dwCheckState = dwCheckState;
   return FWL_Error::Succeeded;
 }
+
+CFWL_ListItem::CFWL_ListItem() {
+  m_rtItem.Reset();
+  m_dwStates = 0;
+  m_wsText = L"";
+  m_pDIB = NULL;
+  m_pData = NULL;
+  m_dwCheckState = 0;
+  m_rtCheckBox.Reset();
+}
+
+CFWL_ListItem::~CFWL_ListItem() {}