Make CFX_{Byte,Wide}String::Remove() no-touch if possible

core/fxcrt/fx_basic_bstring.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 <stddef.h>
 
 #include <algorithm>
 #include <cctype>
@@ skipping 701 matching lines @@
     return;
 
   ReallocBeforeWrite(m_pData->m_nDataLength);
   FXSYS_strupr(m_pData->m_String);
 }
 
 FX_STRSIZE CFX_ByteString::Remove(FX_CHAR chRemove) {
   if (!m_pData || m_pData->m_nDataLength < 1)
     return 0;
 
+  FX_CHAR* pstrSource = m_pData->m_String;
+  FX_CHAR* pstrEnd = m_pData->m_String + m_pData->m_nDataLength;
+  while (pstrSource < pstrEnd) {
+    if (*pstrSource == chRemove)
+      break;
+    pstrSource++;
+  }
+  if (pstrSource == pstrEnd)
+    return 0;
+
+  ptrdiff_t copied = pstrSource - m_pData->m_String;
   ReallocBeforeWrite(m_pData->m_nDataLength);
-  FX_CHAR* pstrSource = m_pData->m_String;
-  FX_CHAR* pstrDest = m_pData->m_String;
-  FX_CHAR* pstrEnd = m_pData->m_String + m_pData->m_nDataLength;
+  pstrSource = m_pData->m_String + copied;
+  pstrEnd = m_pData->m_String + m_pData->m_nDataLength;
+
+  FX_CHAR* pstrDest = pstrSource;
   while (pstrSource < pstrEnd) {
     if (*pstrSource != chRemove) {
       *pstrDest = *pstrSource;
       pstrDest++;
     }
     pstrSource++;
   }
+
   *pstrDest = 0;
   FX_STRSIZE nCount = (FX_STRSIZE)(pstrSource - pstrDest);
   m_pData->m_nDataLength -= nCount;
   return nCount;
 }
 
 FX_STRSIZE CFX_ByteString::Replace(const CFX_ByteStringC& pOld,
                                    const CFX_ByteStringC& pNew) {
   if (!m_pData || pOld.IsEmpty())
     return 0;
@@ skipping 231 matching lines @@
     fraction %= scale;
     scale /= 10;
   }
   return buf_size;
 }
 CFX_ByteString CFX_ByteString::FormatFloat(FX_FLOAT d, int precision) {
   FX_CHAR buf[32];
   FX_STRSIZE len = FX_ftoa(d, buf);
   return CFX_ByteString(buf, len);
 }