Changed the return type for annotation APIs

Before:
    When returning FPDF_ANNOTATION, the APIs would take in a
    FPDF_ANNTOATION* and write the handle of the annotation to it, while
    returning a boolean as status.

This CL:
    This CL changes the APIs to directly return FPDF_ANNOTATION, which
    would be null on failure.
    Also adds more null checks within the annotation APIs.

Bug=pdfium:737

Change-Id: I4f77dd1b16d43eab3f16c303598b76591da0dcab
Reviewed-on: https://pdfium-review.googlesource.com/6952
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Jane Liu <janeliulwq@google.com>

0 files changed, 0 insertions, 0 deletions