GitLab

This CL added the image fetching code that previously lived in clank private repository.

Also I moved android enhanced_bookmark_bridge from
chrome/browser/android/enhanced_bookmarks/ to chrome/browser/enhanced_bookmarks/android,
since the latter is a more unified place to put all files in.(I deleted the
android/enhanced_bookmarks folder).

Last but not least, I made some small changes to the internal implementation of
bookmark_image_service, making it more readable.

The previously private code can be found in code search:
https://cs.corp.google.com/#clankium/src/clank/native/framework/chrome/enhanced_bookmarks/

Downstream CL: https://chrome-internal-review.googlesource.com/#/c/195438/
BUG=454623

Review URL: https://codereview.chromium.org/899653003

Cr-Commit-Position: refs/heads/master@{#314872}