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, 10 insertions, 0 deletions

diff --git a/xfa/fwl/lightwidget/cfwl_combobox.cpp b/xfa/fwl/lightwidget/cfwl_combobox.cpp
index 934b0d856e..9d20c97824 100644
--- a/xfa/fwl/lightwidget/cfwl_combobox.cpp
+++ b/xfa/fwl/lightwidget/cfwl_combobox.cpp
@@ -290,6 +290,12 @@ CFWL_ComboBox::CFWL_ComboBoxDP::CFWL_ComboBoxDP() {
 
 CFWL_ComboBox::CFWL_ComboBoxDP::~CFWL_ComboBoxDP() {}
 
+FWL_Error CFWL_ComboBox::CFWL_ComboBoxDP::GetCaption(
+    IFWL_Widget* pWidget,
+    CFX_WideString& wsCaption) {
+  return FWL_Error::Succeeded;
+}
+
 int32_t CFWL_ComboBox::CFWL_ComboBoxDP::CountItems(IFWL_Widget* pWidget) {
   return m_ItemArray.size();
 }
@@ -427,3 +433,7 @@ FWL_Error CFWL_ComboBox::CFWL_ComboBoxDP::SetItemCheckState(
 FX_FLOAT CFWL_ComboBox::CFWL_ComboBoxDP::GetListHeight(IFWL_Widget* pWidget) {
   return m_fMaxListHeight;
 }
+
+CFWL_ComboBoxItem::CFWL_ComboBoxItem() : m_pDIB(nullptr), m_pData(nullptr) {}
+
+CFWL_ComboBoxItem::~CFWL_ComboBoxItem() {}