GitLab

This CL updates the WebApk proto file to support three additional fields for web share target.
Specifically:

- Method:  can be either GET or POST request.
- Enctype: only relevant for POST method, can be either application/x-www-form-urlencoded
           or multipart/form-data.
           (please note that in the proto file, APPLICATION corresponds with
           application/x-www-form-urlencoded, MULTIPART corresponds with multipart/form-data.)
- Files:   a sequence of share target files. Each share target file contains a name field as an
           identifier, and an accept field that includes a sequence of accepted mime types.

Change-Id: I70f84bf349a5c61519aafcec72a7b68e3f67ef83
Reviewed-on: https://chromium-review.googlesource.com/c/1294595
Commit-Queue: Ethan Xu <xuethan@google.com>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Glenn Hartmann <hartmanng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610746}