After updating flutter for web development my android emulator (Nexus 6 ) is missing from Select Device Option. Only two option shows currently 1. Chrome (Web) and 2. Web Server (Web).
I used following three commands :
flutter channel beta
flutter upgrade
flutter config --enable-web
"I will be grateful for any help you can provide."

Version info[✓] Flutter (Channel beta, v1.15.17, on Linux, locale en_US.UTF-8)
• Flutter version 1.15.17 at /home/parth/Softwares/flutter
• Framework revision 2294d75bfa (3 weeks ago), 2020-03-07 00:28:38 +0900
• Engine revision 5aff311948
• Dart version 2.8.0 (build 2.8.0-dev.12.0 9983424a3c)
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
• Android SDK at /home/parth/Android/Sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.3
• Java binary at: /home/parth/Softwares/android-studio/jre/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)
• All Android licenses accepted.
[✓] Chrome - develop for the web
• Chrome at google-chrome
[✓] Android Studio (version 3.6)
• Android Studio at /home/parth/Softwares/android-studio
• Flutter plugin version 44.0.2
• Dart plugin version 192.7761
• Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)
[✓] VS Code (version 1.43.1)
• VS Code at /usr/share/code
• Flutter extension version 3.8.1
[✓] Connected device (2 available)
• Chrome • chrome • web-javascript • Google Chrome 80.0.3987.149
• Web Server • web-server • web-javascript • Flutter Tools
• No issues found!