Make code compile with clang_use_chrome_plugin (part I)

This change contains files in core/fpdfapi 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/2060973002

1 files changed, 2 insertions, 0 deletions

diff --git a/core/fpdfapi/fpdf_page/cpdf_pageobjectholder.cpp b/core/fpdfapi/fpdf_page/cpdf_pageobjectholder.cpp
index cd6eca5adc..77ec205518 100644
--- a/core/fpdfapi/fpdf_page/cpdf_pageobjectholder.cpp
+++ b/core/fpdfapi/fpdf_page/cpdf_pageobjectholder.cpp
@@ -21,6 +21,8 @@ CPDF_PageObjectHolder::CPDF_PageObjectHolder()
       m_bHasImageMask(FALSE),
       m_ParseState(CONTENT_NOT_PARSED) {}
 
+CPDF_PageObjectHolder::~CPDF_PageObjectHolder() {}
+
 void CPDF_PageObjectHolder::ContinueParse(IFX_Pause* pPause) {
   if (!m_pParser) {
     return;