UserAgent: Mozilla/5.0 (Windows NT 5.1; rv:49.0) Gecko/20100101 Firefox/49.0

Steps to reproduce the problem:
args.gn:
---------
enable_nacl=false
treat_warnings_as_errors=false
proprietary_codecs=true
ffmpeg_branding="Chrome"
linux_use_bundled_binutils=false
clang_use_chrome_plugins=false
cc_wrapper="icecc"
is_debug=false
target_cpu="arm64"

build log:
-----------
In file included from ../native_client/src/shared/platform/nacl_secure_random_common.c:11:
In file included from ../native_client/src/shared/platform/nacl_log.h:61:
../native_client/src/include/portability.h:90:2: error: Unrecognized host architecture
#error Unrecognized host architecture
 ^
1 error generated.

In file included from ../native_client/src/shared/platform/nacl_interruptible_mutex.c:12:
../native_client/src/include/portability.h:90:2: error: Unrecognized host architecture
#error Unrecognized host architecture
 ^

...

I set enable_nacl=false, but it seems the build system ignores it and tries to build nacl, which isn't supported on AArch64.

What is the expected behavior?

What went wrong?
The build is broken.

Did this work before? N/A 

Chrome version:   Channel: n/a
OS Version: 
Flash Version: