Wrapper class for annotation dictionary + CPDF_Form

Simple wrapper class for annotation + its path parsing form object. This
will be used in APIs for extracting and setting annotation paths.

Bug=pdfium:737

Change-Id: I2e8131672d087613213735295c6d01e377b956e7
Reviewed-on: https://pdfium-review.googlesource.com/6730
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
diff --git a/public/fpdf_annot.h b/public/fpdf_annot.h
index adfddec..bd18898 100644
--- a/public/fpdf_annot.h
+++ b/public/fpdf_annot.h
@@ -97,6 +97,13 @@
                                               int index,
                                               FPDF_ANNOTATION* annot);
 
+// Close an annotation. Must be called when the annotation returned by
+// FPDFPage_CreateAnnot() or FPDFPage_GetAnnot() is no longer needed. This
+// function does not remove the annotation from the document.
+//
+//   annot  - handle to an annotation.
+DLLEXPORT void STDCALL FPDFPage_CloseAnnot(FPDF_ANNOTATION annot);
+
 // Get the subtype of an annotation.
 //
 //   annot  - handle to an annotation.