Rename CPDF_{Byte,Wide}String::AsSpan() to span()

Makes these method names consistent between strings and string views,
so that templates may more easily be applied to both.

-- CPDF_ByteString::AsRawSpan() renamed to raw_span().

Change-Id: If957ecb99987bf70885e1cd62b837e216a60acaa
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/57950
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_interactiveform.cpp b/fpdfsdk/cpdfsdk_interactiveform.cpp
index 2fee643..67fa3e3 100644
--- a/fpdfsdk/cpdfsdk_interactiveform.cpp
+++ b/fpdfsdk/cpdfsdk_interactiveform.cpp
@@ -101,7 +101,7 @@
     name = pField->GetUnicodeTextFor("T");
     ByteString name_b = name.ToDefANSI();
     ByteString csBValue = pField->GetStringFor("V");
-    WideString csWValue = PDF_DecodeText(csBValue.AsRawSpan());
+    WideString csWValue = PDF_DecodeText(csBValue.raw_span());
     ByteString csValue_b = csWValue.ToDefANSI();
     fdfEncodedData << name_b << "=" << csValue_b;
     if (i != pFields->size() - 1)