Not seeing this on bots, but getting it locally for some reason. 

util.build_utils.CalledProcessError: Command failed: ( cd /usr/local/google/home/agrieve/ssd/git/chromium-android/src/out-gn/Release; java -jar ../../third_party/proguard/lib/proguard.jar -forc
eprocessing -libraryjars ../../third_party/android_tools/sdk/platforms/android-23/android.jar -injars gen/chrome/android/chrome_public_apk/chrome_public_apk.jar:lib.java/third_party/gif_player/
gif_player_java.jar:lib.java/third_party/leakcanary/leakcanary_noop_java.jar:lib.java/chrome/android/webapk/libs/common/common_java.jar:lib.java/third_party/WebKit/public/blink_headers_java.jar
:lib.java/third_party/android_tools/android_support_v13_java.jar:lib.java/third_party/android_tools/android_support_multidex_java.jar:lib.java/third_party/jsr-305/jsr_305_javalib.jar:lib.java/u
i/accessibility/ui_accessibility_java.jar:lib.java/third_party/android_tools/legacy_http_javalib.jar:lib.java/base/base_java.jar:lib.java/components/bookmarks/common/android/bookmarks_java.jar:
lib.java/components/variations/android/variations_java.jar:lib.java/media/capture/video/android/capture_java.jar:lib.java/third_party/android_data_chart/android_data_chart_java.jar:lib.java/chr
ome/android/webapk/libs/client/client_java.jar:lib.java/third_party/android_swipe_refresh/android_swipe_refresh_java.jar:lib.java/components/safe_json/android/safe_json_java.jar:lib.java/media/
midi/midi_java.jar:lib.java/components/navigation_interception/android/navigation_interception_java.jar:lib.java/third_party/android_protobuf/protobuf_nano_javalib.jar:lib.java/components/web_r
estrictions/web_restrictions_java.jar:lib.java/printing/printing_java.jar:lib.java/third_party/cardboard-java/cardboard-java.jar:lib.java/third_party/android_tools/android_gcm_java.jar:lib.java
/mojo/public/java/system.jar:lib.java/device/bluetooth/java.jar:lib.java/mojo/public/java/bindings.jar:lib.java/device/battery/mojo_bindings_java.jar:lib.java/third_party/WebKit/public/android_
mojo_bindings_java.jar:lib.java/third_party/custom_tabs_client/custom_tabs_support_lib.jar:lib.java/components/policy/android/policy_java.jar:lib.java/net/android/net_java.jar:lib.java/mojo/and
roid/system_java.jar:lib.java/ui/android/ui_java.jar:lib.java/components/precache/android/precache_java.jar:lib.java/third_party/android_tools/android_support_design_java.jar:lib.java/third_par
ty/android_tools/android_support_v7_appcompat_java.jar:lib.java/third_party/cacheinvalidation/cacheinvalidation_proto_java.jar:lib.java/device/usb/java.jar:lib.java/device/vr/java.jar:lib.java/
components/invalidation/impl/proto_java.jar:lib.java/media/base/android/media_java.jar:lib.java/components/dom_distiller/android/dom_distiller_core_java.jar:lib.java/device/battery/android/batt
ery_monitor_android.jar:lib.java/chrome/android/document_tab_model_info_proto_java.jar:lib.java/device/power_save_blocker/java.jar:lib.java/device/vibration/mojo_bindings_java.jar:lib.java/thir
d_party/android_tools/android_support_v7_recyclerview_java.jar:lib.java/third_party/android_tools/android_support_v7_mediarouter_java.jar:lib.java/third_party/android_media/android_media_java.j
ar:lib.java/third_party/android_tools/google_play_services_default_java.jar:lib.java/device/vibration/android/vibration_manager_android.jar:lib.java/third_party/cacheinvalidation/cacheinvalidat
ion_javalib.jar:lib.java/components/gcm_driver/instance_id/android/instance_id_driver_java.jar:lib.java/sync/android/sync_java.jar:lib.java/components/signin/core/browser/android/java.jar:lib.j
ava/content/public/android/content_java.jar:lib.java/components/web_contents_delegate_android/web_contents_delegate_android_java.jar:lib.java/components/gcm_driver/android/gcm_driver_java.jar:l
ib.java/components/service_tab_launcher/service_tab_launcher_java.jar:lib.java/components/invalidation/impl/java.jar:lib.java/components/dom_distiller/android/dom_distiller_content_java.jar:lib
.java/chrome/android/chrome_java.jar -include gen/chrome/android/chrome_public_apk/chrome_public_apk.resources.proguard.txt -include ../../chrome/android/java/proguard.flags -outjars gen/chrome
/android/chrome_public_apk/chrome_public_apk.proguard.jar -dump gen/chrome/android/chrome_public_apk/chrome_public_apk.proguard.jar.dump -printseeds gen/chrome/android/chrome_public_apk/chrome_
public_apk.proguard.jar.seeds -printusage gen/chrome/android/chrome_public_apk/chrome_public_apk.proguard.jar.usage -printmapping gen/chrome/android/chrome_public_apk/chrome_public_apk.proguard
.jar.mapping )
Warning: library class android.webkit.WebView depends on program class android.net.http.SslCertificate
Warning: library class android.webkit.WebView depends on program class android.net.http.SslCertificate
Warning: there were 2 instances of library classes depending on program classes.
         You must avoid such dependencies, since the program classes will
         be processed, while the library classes will remain unchanged.
Error: Please correct the above warnings first.

It does seem legitimate though. It appears we're compiling in:
third_party/android_tools/legacy_http_javalib.jar

Which contains a class that ../../third_party/android_tools/sdk/platforms/android-23/android.jar depends on.

The reason this could be possible is that this was a set of classes that used to exist on Android, and still actually does, but that has been removed from android.jar (the interface library used for compiling).

I believe the fix for this is to add legacy_http_javalib.jar to the CLASSPATH, but don't bundle it in.