Note: this format does not yet pass validation tests.
Add skia_pdf_generate_pdfa GYP flag. Default to off for now.
PDF/A files are not reproducable, so they make correctness
testing harder.
Turn the Metadata struct into te SkPDFMetadata struct. This
splits out a lot of functionality around both kinds of metadata.
When PDF/A is used, add an ID entry to the trailer.
Add SkPDFObjNumMap::addObjectRecursively.
Test with
GYP_DEFINES=skia_pdf_generate_pdfa=1 bin/sync-and-gyp
ninja -C out/Release dm
out/Release/dm --config pdf --src skp gm -w /tmp/dm
With skia_pdf_generate_pdfa=0, all PDFs generated from GMs and
SKPs are identical. With skia_pdf_generate_pdfa=1, all PDFs
generated from GMs and SKPs render identically in Pdfium.
BUG=skia:3110
Review URL: https://codereview.chromium.org/1394263003
34422610ac