use armeabi-v7a

-# Originally based on https://medium.com/@nocnoc/flutter-unit-widget-and-integration-testing-with-ios-and-android-emulators-on-travis-ci-df17ed7c3be
 sudo: true
 
 matrix:
@@ -23,7 +22,7 @@ matrix:
           - extra-google-m2repository
           - extra-android-m2repository
 
-          - sys-img-x86-android-26
+          - sys-img-armeabi-v7a-android-26
 
       install:
         - git clone -b master https://github.com/flutter/flutter.git
@@ -32,7 +31,7 @@ matrix:
         - export PATH="$PATH":"$HOME/.pub-cache/bin"
         - export PATH=$PWD/flutter/bin:$PWD/flutter/bin/cache/dart-sdk/bin:$PATH
 
-        - echo no | android create avd --force -n test -t android-26 --abi default/x86 -c 100M
+        - echo no | android create avd --force -n test -t android-26 --abi armeabi-v7a -c 100M
         - emulator -avd test -no-audio -no-window &
         - android-wait-for-emulator
         - adb shell input keyevent 82 &