Rename both As{Byte,Wide}StringC() helpers to AsStringC().

The naming is redundant given the base type, and will stand
in the way of consolidating Byte and Wide code.

BUG=

Review URL: https://codereview.chromium.org/1862123003
diff --git a/fpdfsdk/fsdk_baseannot.cpp b/fpdfsdk/fsdk_baseannot.cpp
index b3363bf..68d99e8 100644
--- a/fpdfsdk/fsdk_baseannot.cpp
+++ b/fpdfsdk/fsdk_baseannot.cpp
@@ -831,22 +831,22 @@
 
   if (sAPState.IsEmpty()) {
     pParentDict = pAPDict;
-    pStream = pAPDict->GetStreamBy(sAPType.AsByteStringC());
+    pStream = pAPDict->GetStreamBy(sAPType.AsStringC());
   } else {
-    CPDF_Dictionary* pAPTypeDict = pAPDict->GetDictBy(sAPType.AsByteStringC());
+    CPDF_Dictionary* pAPTypeDict = pAPDict->GetDictBy(sAPType.AsStringC());
     if (!pAPTypeDict) {
       pAPTypeDict = new CPDF_Dictionary;
-      pAPDict->SetAt(sAPType.AsByteStringC(), pAPTypeDict);
+      pAPDict->SetAt(sAPType.AsStringC(), pAPTypeDict);
     }
     pParentDict = pAPTypeDict;
-    pStream = pAPTypeDict->GetStreamBy(sAPState.AsByteStringC());
+    pStream = pAPTypeDict->GetStreamBy(sAPState.AsStringC());
   }
 
   if (!pStream) {
     pStream = new CPDF_Stream(nullptr, 0, nullptr);
     CPDF_Document* pDoc = m_pPageView->GetPDFDocument();
     int32_t objnum = pDoc->AddIndirectObject(pStream);
-    pParentDict->SetAtReference(sAPType.AsByteStringC(), pDoc, objnum);
+    pParentDict->SetAtReference(sAPType.AsStringC(), pDoc, objnum);
   }
 
   CPDF_Dictionary* pStreamDict = pStream->GetDict();