Avoid copying in TrimRight() and TrimLeft() 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 823 matching lines @@
   if (this_len > that_len) {
     return 1;
   }
   return 0;
 }
 
 void CFX_ByteString::TrimRight(const CFX_ByteStringC& pTargets) {
   if (!m_pData || pTargets.IsEmpty()) {
     return;
   }
-  ReallocBeforeWrite(m_pData->m_nDataLength);
   FX_STRSIZE pos = GetLength();
   if (pos < 1) {
     return;
   }
   while (pos) {
     FX_STRSIZE i = 0;
     while (i < pTargets.GetLength() &&
            pTargets[i] != m_pData->m_String[pos - 1]) {
       i++;
     }
     if (i == pTargets.GetLength()) {
       break;
     }
     pos--;
   }
   if (pos < m_pData->m_nDataLength) {
+    ReallocBeforeWrite(m_pData->m_nDataLength);
     m_pData->m_String[pos] = 0;
     m_pData->m_nDataLength = pos;
   }
 }
 
 void CFX_ByteString::TrimRight(FX_CHAR chTarget) {
   TrimRight(CFX_ByteStringC(chTarget));
 }
 
 void CFX_ByteString::TrimRight() {
   TrimRight("\x09\x0a\x0b\x0c\x0d\x20");
 }
 
 void CFX_ByteString::TrimLeft(const CFX_ByteStringC& pTargets) {
   if (!m_pData || pTargets.IsEmpty())
     return;
 
   FX_STRSIZE len = GetLength();
   if (len < 1)
     return;
 
-  ReallocBeforeWrite(len);
   FX_STRSIZE pos = 0;
   while (pos < len) {
     FX_STRSIZE i = 0;
     while (i < pTargets.GetLength() && pTargets[i] != m_pData->m_String[pos]) {
       i++;
     }
     if (i == pTargets.GetLength()) {
       break;
     }
     pos++;
   }
   if (pos) {
+    ReallocBeforeWrite(len);
     FX_STRSIZE nDataLength = len - pos;
     FXSYS_memmove(m_pData->m_String, m_pData->m_String + pos,
                   (nDataLength + 1) * sizeof(FX_CHAR));
     m_pData->m_nDataLength = nDataLength;
   }
 }
 
 void CFX_ByteString::TrimLeft(FX_CHAR chTarget) {
   TrimLeft(CFX_ByteStringC(chTarget));
 }
@@ skipping 69 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);
 }