Created libcurl_on_cronet directory with OWNERS and README.md

Bug:973603

R=caraitto@chromium.org, pauljensen@chromium.org

Change-Id: Ia1d3309579ee45b222375b12cd655ee1d985a07a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1652540
Auto-Submit: Michelle Roxas <michelleroxas@google.com>
Commit-Queue: Michelle Roxas <michelleroxas@google.com>
Reviewed-by: Paul Jensen <pauljensen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#681800}

components/cronet/libcurl_on_cronet/OWNERS

+caraitto@chromium.org
+pauljensen@chromium.org

components/cronet/libcurl_on_cronet/README.md

+# libcurl_on_cronet - libcurl wrapper on Cronet native API
+
+The libcurl_on_cronet library is a C++ wrapper library implemented via the
+Cronet Native C API, providing synchronous behavior for URL requests using
+the Chrome Network Stack. It uses the
+[libcurl-easy](https://curl.haxx.se/libcurl/c/libcurl-easy.html) C89 interface,
+the subset of libcurl's C API that supports synchronous URL transfers, and is
+implemented in C++ 14.
+
+## Overview
+
+The Cronet library provides a cross-platform Native API on top of the Chrome
+Network Stack, making it possible to use advanced protocols that would
+otherwise be difficult for an application to implement from scratch. The base
+asynchronous API offered by Cronet requires little overhead on top of the
+Chrome Network Stack, optimizing performance. However, it is non-trivial
+to get started using it for URL transfers, as it requires implementation of
+asynchronous components such as executors and callbacks regardless of whether
+the consuming application has or supports asynchronous, multithreaded behavior.
+
+To lower the bar for trying out Cronet, this library supports synchronous URL
+requests by implementing the underlying details required by the base
+asynchronous API. It defines a minimally functional executor and
+callback and handles management of the Cronet Engine and UrlRequest objects,
+supporting a subset of the configuration options available in the
+libcurl-easy API. This allows developers who are already familiar with libcurl 
+to more easily try out Cronet, without having to initially learn a new interface 
+and its corresponding workflow.
+
+### Command Line Tool
+
+There are also plans to develop a command line tool that can invoke a subset of
+the implemented API functions in the terminal. This would aid in debugging
+networking issues or test the functionality of the Chrome Network Stack in an
+easily reproducible manner, acting as a lightweight end-to-end integration test
+of the stack without the bulk of the rest of the Chromium browser. With a
+simpler binary it would be easier to narrow down the possible points of failure
+and pinpoint the root cause of a specific networking issue.
+
+This tool uses the same command line flags as the curl command supported by
+libcurl, supporting only a smaller subset of curl's available options. This
+smaller binary would be easier to debug and maintain while still maintaining
+a sense of familiarity, allowing for easy compatibility with the
+["copy as cURL"](https://developers.google.com/web/updates/2015/05/replay-a-network-request-in-curl)
+Chromium devtools feature.
+
+This library is currently in active development.
+
+## Details
+
+TODO(michelleroxas): Add more description to this as the project details
+become more fleshed out.