Replace calls to deprecated CFX_{Wide,Byte}String::Empty()

core/fxcodec/lgif/fx_gif.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/fxcodec/lgif/fx_gif.h"
 
 #include "core/fxcodec/lbmp/fx_bmp.h"
 
@@ skipping 629 matching lines @@
 int32_t gif_decode_extension(gif_decompress_struct_p gif_ptr) {
   uint8_t* data_size_ptr = NULL;
   uint8_t* data_ptr = NULL;
   uint32_t skip_size_org = gif_ptr->skip_size;
   switch (gif_ptr->decode_status) {
     case GIF_D_STATUS_EXT_CE: {
       if (gif_read_data(gif_ptr, &data_size_ptr, 1) == NULL) {
         gif_ptr->skip_size = skip_size_org;
         return 2;
       }
-      gif_ptr->cmt_data_ptr->Empty();
+      gif_ptr->cmt_data_ptr->clear();
       while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
         uint8_t data_size = *data_size_ptr;
         if (gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) == NULL ||
             gif_read_data(gif_ptr, &data_size_ptr, 1) == NULL) {
           gif_ptr->skip_size = skip_size_org;
           return 2;
         }
         *(gif_ptr->cmt_data_ptr) +=
             CFX_ByteString((const FX_CHAR*)data_ptr, data_size);
       }
@@ skipping 559 matching lines @@
     gif_ptr->cur_offset = cur_offset;
     res = FALSE;
   }
   dst_len = gif_ptr->cur_offset;
   dst_buf[dst_len - 1] = GIF_SIG_TRAILER;
   if (res) {
     gif_ptr->frames++;
   }
   return res;
 }