What event code needs to be sent for the overview key with adb shell input keyevent <code>
?
Assuming you mean the button that shows the list of opened apps, it's KEYCODE_APP_SWITCH:
KEYCODE_APP_SWITCH
Added in API level 11 int KEYCODE_APP_SWITCH Key code constant: App switch key. Should bring up the application switcher dialog.
Constant Value: 187 (0x000000bb)
For using it with adb shell input, you can simply use the name:
adb shell input keyevent KEYCODE_APP_SWITCH