Implement FPDF_VIEWERREF_GetName() API.

testing/resources/viewer_ref.in

Index: testing/resources/viewer_ref.in
diff --git a/testing/resources/viewer_ref.in b/testing/resources/viewer_ref.in
new file mode 100644
index 0000000000000000000000000000000000000000..62ae372dfe905cc54ddd47d81e1968347894991c
--- /dev/null
+++ b/testing/resources/viewer_ref.in
@@ -0,0 +1,57 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+  /ViewerPreferences <<
+    /Foo /foo
+    /HideToolbar true
+    /Direction /R2L
+    /ViewArea /CropBox
+    /NumCopies 5
+  >>
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /Count 1
+  /Kids [
+    3 0 R
+  ]
+>>
+endobj
+% Page number 0.
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Resources <<
+    /Font <</F1 15 0 R>>
+  >>
+  /Contents [21 0 R]
+  /MediaBox [0 0 612 792]
+>>
+endobj
+% Font resource.
+{{object 15 0}} <<
+  /Type /Font
+  /Subtype /Type1
+  /BaseFont /Arial
+>>
+endobj
+% Content for page 0.
+{{object 21 0}} <<
+  /Length 0
+>>
+stream
+BT
+/F1 20 Tf
+100 600 TD (Page1)Tj
+ET
+endstream
+endobj
+{{xref}}
+trailer <<
+  /Size 6
+  /Root 1 0 R
+>>
+{{startxref}}
+%%EOF