Use string pools in some dictionaries

fpdfsdk/fpdfdoc_unittest.cpp

Index: fpdfsdk/fpdfdoc_unittest.cpp
diff --git a/fpdfsdk/fpdfdoc_unittest.cpp b/fpdfsdk/fpdfdoc_unittest.cpp
index 5bda8da9282af3dae5f72589ee06b7784a2429d5..8181851a5fc38fd46741409734f348fb279a6b7c 100644
--- a/fpdfsdk/fpdfdoc_unittest.cpp
+++ b/fpdfsdk/fpdfdoc_unittest.cpp
@@ -64,7 +64,7 @@ class PDFDocTest : public testing::Test {
     m_pDoc.reset(new CPDF_TestPdfDocument());
     m_pIndirectObjs = m_pDoc->GetHolder();
     // Setup the root directory.
-    m_pRootObj.reset(new CPDF_Dictionary());
+    m_pRootObj.reset(new CPDF_Dictionary(nullptr));
     m_pDoc->SetRoot(m_pRootObj.get());
   }
 
@@ -79,7 +79,7 @@ class PDFDocTest : public testing::Test {
     std::vector<DictObjInfo> info;
     for (int i = 0; i < num; ++i) {
       // Objects created will be released by the document.
-      CPDF_Dictionary* obj(new CPDF_Dictionary());
+      CPDF_Dictionary* obj(new CPDF_Dictionary(nullptr));
       m_pIndirectObjs->AddIndirectObject(obj);
       info.push_back({obj->GetObjNum(), obj});
     }
@@ -104,7 +104,7 @@ TEST_F(PDFDocTest, FindBookmark) {
   }
   {
     // Empty bookmark tree.
-    m_pRootObj->SetFor("Outlines", new CPDF_Dictionary());
+    m_pRootObj->SetFor("Outlines", new CPDF_Dictionary(nullptr));
     std::unique_ptr<unsigned short, pdfium::FreeDeleter> title =
         GetFPDFWideString(L"");
     EXPECT_EQ(nullptr, FPDFBookmark_Find(m_pDoc.get(), title.get()));