Make code compile with clang_use_chrome_plugin (part V)chromium/2770

This change mainly contains files in xfa/fxfa 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/2071683002

1 files changed, 1 insertions, 1 deletions

diff --git a/xfa/fxfa/parser/xfa_doclayout.h b/xfa/fxfa/parser/xfa_doclayout.h
index a0b29e5ff8..cc0cf82417 100644
--- a/xfa/fxfa/parser/xfa_doclayout.h
+++ b/xfa/fxfa/parser/xfa_doclayout.h
@@ -66,7 +66,7 @@ class CXFA_ContainerLayoutItem : public CXFA_LayoutItem {
 class CXFA_ContentLayoutItem : public CXFA_LayoutItem {
  public:
   CXFA_ContentLayoutItem(CXFA_Node* pNode);
-  virtual ~CXFA_ContentLayoutItem();
+  ~CXFA_ContentLayoutItem() override;
 
   CXFA_ContentLayoutItem* m_pPrev;
   CXFA_ContentLayoutItem* m_pNext;