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

core/fxcodec/codec/fx_codec_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/codec/codec_int.h"
 #include "core/fxcodec/include/fx_codec.h"
 #include "core/fxcodec/lgif/fx_gif.h"
 #include "core/fxge/include/fx_dib.h"
@@ skipping 142 matching lines @@
       pAttribute->m_fAspectRatio = ctx->gif_ptr->pixel_aspect;
       if (ctx->gif_ptr->cmt_data_ptr) {
         const uint8_t* buf =
             (const uint8_t*)ctx->gif_ptr->cmt_data_ptr->GetBuffer(0);
         uint32_t len = ctx->gif_ptr->cmt_data_ptr->GetLength();
         if (len > 21) {
           uint8_t size = *buf++;
           if (size) {
             pAttribute->m_strAuthor = CFX_ByteString(buf, size);
           } else {
-            pAttribute->m_strAuthor.Empty();
+            pAttribute->m_strAuthor.clear();
           }
           buf += size;
           size = *buf++;
           if (size == 20) {
             FXSYS_memcpy(pAttribute->m_strTime, buf, size);
           }
         }
       }
     }
   }
   return ret;
 }
 
 uint32_t CCodec_GifModule::GetAvailInput(FXGIF_Context* ctx,
                                          uint8_t** avial_buf_ptr) {
   return gif_get_avail_input(ctx->gif_ptr, avial_buf_ptr);
 }
 
 void CCodec_GifModule::Input(FXGIF_Context* ctx,
                              const uint8_t* src_buf,
                              uint32_t src_size) {
   gif_input_buffer(ctx->gif_ptr, (uint8_t*)src_buf, src_size);
 }