Make code compile with clang_use_chrome_plugin (part II)

This change contains files in core directory which were not covered
in part I. 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/2060913003

1 files changed, 19 insertions, 0 deletions

diff --git a/core/fxcodec/lgif/fx_gif.cpp b/core/fxcodec/lgif/fx_gif.cpp
index b9ea090853..d6db28b427 100644
--- a/core/fxcodec/lgif/fx_gif.cpp
+++ b/core/fxcodec/lgif/fx_gif.cpp
@@ -12,9 +12,28 @@ void CGifLZWDecoder::Input(uint8_t* src_buf, uint32_t src_size) {
   next_in = src_buf;
   avail_in = src_size;
 }
+
 uint32_t CGifLZWDecoder::GetAvailInput() {
   return avail_in;
 }
+
+CGifLZWDecoder::CGifLZWDecoder(FX_CHAR* error_ptr)
+    : code_size(0),
+      code_size_cur(0),
+      code_clear(0),
+      code_end(0),
+      code_next(0),
+      code_first(0),
+      stack_size(0),
+      code_old(0),
+      next_in(nullptr),
+      avail_in(0),
+      bits_left(0),
+      code_store(0),
+      err_msg_ptr(error_ptr) {}
+
+CGifLZWDecoder::~CGifLZWDecoder() {}
+
 void CGifLZWDecoder::InitTable(uint8_t code_len) {
   code_size = code_len;
   code_clear = 1 << code_size;