GitLab

Move the resources for the pdf plugin out of //content into //components. Also,
reuse the same code for getting the resource from PepperPDFHost and
PPB_PDF_Impl.

BUG=401242
R=blundell@chromium.org, jam@chromium.org, raymes@chromium.org

Review URL: https://codereview.chromium.org/506473003

Cr-Commit-Position: refs/heads/master@{#292897}