UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3472.3 Safari/537.36

Steps to reproduce the problem:
1. Get latest chromium code e2fcd4b0fce6f48b
2. gn gen --args='target_cpu="arm64" is_debug=false is_component_build=false' out/arm64_release
3. ninja -C out/arm64_release chrome unstable_deb

What is the expected behavior?
Able to build out the arm64 chrome deb package.

What went wrong?
//chrome/installer/linux:calculate_deb_dependencies(//build/toolchain/linux:clang_arm64)
FAILED: deb_chrome_sandbox.deps 
python ../../chrome/installer/linux/debian/calculate_package_deps.py chrome_sandbox ../../build/linux/debian_sid_arm64-sysroot arm64 deb_chrome_sandbox.deps
Unsupported architecture arm64
[68/73] ACTION //chrome/installer/linux:calculate_deb_dependencies(//build/toolchain/linux:clang_arm64)
FAILED: deb_chrome.deps 
python ../../chrome/installer/linux/debian/calculate_package_deps.py chrome ../../build/linux/debian_sid_arm64-sysroot arm64 deb_chrome.deps
Unsupported architecture arm64
ninja: build stopped: subcommand failed.

Did this work before? N/A 

Chrome version: 69.0.3472.3  Channel: canary
OS Version: 
Flash Version: