How to get Cronet Android headers to use with cronet.so in JNI (C++)?

I'm trying to use Cronet on Android directly from my JNI / C++ layer, not through the Java API.

I already have the cronet.so (from Play Services / build output).

What I'm missing are the headers (like cronet_c.h / cronet.idl_c.h) so that I can call the Cronet C API functions (Cronet_Engine_Create, Cronet_UrlRequest_Create, etc.) directly from native code.

I tried building Chromium multiple times to extract the headers, but each attempt failed due to build complexity and system issues.

My question

👉 Is there a place to download or obtain the prebuilt Cronet headers for Android?

I don't want to go through the Java APIs and wrap them in JNI — I want to link against cronet.so directly from C++.

If not, then just help me with my building process wehre im failing, and what could be the solutions.

What I tried:

I attempted to build Chromium several times in order to extract the headers, but the build process failed multiple times due to complexity and system issues.

I couldn't find any official prebuilt SDK or standalone header package for Android.

I also tried a minimal build script:

#!/bin/bash
set -e

WORKDIR="$HOME/cronet_build"
DEPOT_TOOLS="$WORKDIR/depot_tools"
SRC_DIR="$WORKDIR/src"
OUT_DIR="$SRC_DIR/out/Release"

sudo apt-get update
sudo apt-get install -y git python3 curl unzip gnupg build-essential clang lld ninja-build pkg-config libnss3 libnss3-dev openjdk-17-jdk

if [ ! -d "$DEPOT_TOOLS" ]; then
    git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git "$DEPOT_TOOLS"
fi
export PATH="$DEPOT_TOOLS:$PATH"

mkdir -p "$WORKDIR"
cd "$WORKDIR"
fetch --nohooks chromium

cd "$SRC_DIR"
gclient sync --with-branch-heads

gn gen "$OUT_DIR" --args='
is_debug=false
target_os="android"
target_cpu="arm64"
is_cronet_package=true
'

autoninja -C "$OUT_DIR" cronet_package

That failed with an error about siso not found.

Then I tried again with updated args:

gn gen "$HOME/release" --args='
is_debug=false
target_os="android"
target_cpu="arm64"
is_component_build=false
use_siso=false
'

This succeeded in generating targets:

Done. Made 57416 targets from 4018 files in 15328ms

But when I tried to build:

cd ~/cronet_build/src
autoninja -C ~/release cronet

I got:

ninja: error: unknown target 'cronet', did you mean 'root'?

And with:

autoninja -C ~/release cronet_package

I got:

ninja: error: unknown target 'cronet_package'

What I expected:

A way to obtain the Cronet headers separately (without building Chromium fully).

Ideally, an official or reliable source for downloading the headers so I can include them in my NDK/JNI project and link against cronet.so.