GitLab

- Copy Android relocation packer source from AOSP:
    bionic/tools/relocation_packer/
- Remove golden test data generation scripts (not needed here)
- Add a local ScopedFd.h, to avoid any dependency on base
- Add gyp and gn build files for chromium
- Update third_party/android_platform/README.chromium

BUG=385553
R=rmcilroy@chromium.org

Review URL: https://codereview.chromium.org/1027823002

Cr-Commit-Position: refs/heads/master@{#322401}