Make CPDF_Dictionary methods take CFX_ByteString arguments

This will help avoid duplicate allocation of CFX_ByteStrings
when the caller already has one.  It may seem counter-intuitive
that requiring the caller to pass an allocated CFX_ByteString
rather than a static CFX_ByteStringC would improve the situation,
but due to the idiosyncrasies of std::map, the CPDF_Dictionary
methods must always do an allocation under the covers which
can't be avoided.

The changed callers in this CL are places where we would
previously demote to CFX_ByteStringC and then allocate a
a duplicate CFX_ByteString in the dictionary method.

Review URL: https://codereview.chromium.org/1889863002

1 files changed, 3 insertions, 4 deletions

diff --git a/core/fpdfdoc/doc_tagged.cpp b/core/fpdfdoc/doc_tagged.cpp
index b60c83932e..f559c0ac2b 100644
--- a/core/fpdfdoc/doc_tagged.cpp
+++ b/core/fpdfdoc/doc_tagged.cpp
@@ -205,7 +205,7 @@ CPDF_StructElementImpl::CPDF_StructElementImpl(CPDF_StructTreeImpl* pTree,
   m_pDict = pDict;
   m_Type = pDict->GetStringBy("S");
   if (pTree->m_pRoleMap) {
-    CFX_ByteString mapped = pTree->m_pRoleMap->GetStringBy(m_Type.AsStringC());
+    CFX_ByteString mapped = pTree->m_pRoleMap->GetStringBy(m_Type);
     if (!mapped.IsEmpty()) {
       m_Type = mapped;
     }
@@ -373,15 +373,14 @@ CPDF_Object* CPDF_StructElementImpl::GetAttr(const CFX_ByteStringC& owner,
   if (CPDF_Array* pArray = pC->AsArray()) {
     for (uint32_t i = 0; i < pArray->GetCount(); i++) {
       CFX_ByteString class_name = pArray->GetStringAt(i);
-      CPDF_Dictionary* pClassDict =
-          pClassMap->GetDictBy(class_name.AsStringC());
+      CPDF_Dictionary* pClassDict = pClassMap->GetDictBy(class_name);
       if (pClassDict && pClassDict->GetStringBy("O") == owner)
         return pClassDict->GetDirectObjectBy(name);
     }
     return nullptr;
   }
   CFX_ByteString class_name = pC->GetString();
-  CPDF_Dictionary* pClassDict = pClassMap->GetDictBy(class_name.AsStringC());
+  CPDF_Dictionary* pClassDict = pClassMap->GetDictBy(class_name);
   if (pClassDict && pClassDict->GetStringBy("O") == owner)
     return pClassDict->GetDirectObjectBy(name);
   return nullptr;