//pdf contains the PDF plugin, its Blink-based replacement, as well as PDF utility functions that leverage PDFium. It can use low-level components that live below the content layer, as well as other foundational code like //printing. It should not use //content or anything in //components that lives above the content layer. Code that lives above the content layer should live in //components/pdf, or in the embedder. All the code here should run in sandboxed child processes.

TODO(crbug.com/1220865): Remove existing //content dependencies.