Take advantage of implicit std::unique_ptr<>(nulltpr_t) ctor.

core/fpdfapi/page/cpdf_clippath.cpp

 // Copyright 2016 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/fpdfapi/page/cpdf_clippath.h"
 
 #include <utility>
 
@@ skipping 82 matching lines @@
   }
   pData->m_PathAndTypeList.push_back(std::make_pair(path, type));
 }
 
 void CPDF_ClipPath::AppendTexts(
     std::vector<std::unique_ptr<CPDF_TextObject>>* pTexts) {
   PathData* pData = m_Ref.GetPrivateCopy();
   if (pData->m_TextList.size() + pTexts->size() <= FPDF_CLIPPATH_MAX_TEXTS) {
     for (size_t i = 0; i < pTexts->size(); i++)
       pData->m_TextList.push_back(std::move((*pTexts)[i]));
-    pData->m_TextList.push_back(std::unique_ptr<CPDF_TextObject>());
+    pData->m_TextList.push_back(nullptr);
   }
   pTexts->clear();
 }
 
 void CPDF_ClipPath::Transform(const CFX_Matrix& matrix) {
   PathData* pData = m_Ref.GetPrivateCopy();
   for (auto& obj : pData->m_PathAndTypeList)
     obj.first.Transform(&matrix);
   for (auto& text : pData->m_TextList) {
     if (text)
       text->Transform(matrix);
   }
 }
 
 CPDF_ClipPath::PathData::PathData() {}
 
 CPDF_ClipPath::PathData::PathData(const PathData& that) {
   m_PathAndTypeList = that.m_PathAndTypeList;
 
   m_TextList.resize(that.m_TextList.size());
   for (size_t i = 0; i < that.m_TextList.size(); ++i) {
     if (that.m_TextList[i])
       m_TextList[i].reset(that.m_TextList[i]->Clone());
   }
 }
 
 CPDF_ClipPath::PathData::~PathData() {}