I presume it is the same as using SMS which I have been playing with.
When using in phone gap you have to add a plugin to do the work.
There is a plugin here https://www.npmjs.com/package/cordova-plugin-googlemaps
<plugin name="cordova-plugin-googlemaps" spec="2.0.0">
<variable name="API_KEY_FOR_ANDROID" value="YOUR_ANDROID_API_KEY_IS_HERE" />
<variable name="API_KEY_FOR_IOS" value="YOUR_IOS_API_KEY_IS_HERE" />
<variable name="LOCATION_WHEN_IN_USE_DESCRIPTION" value="My custom when in use message" />
<variable name="LOCATION_ALWAYS_USAGE_DESCRIPTION" value="My custom always usage message" />
</plugin>
So you have to add this to you project properties - config.xml
Hopefully this will do the trick.
Cheers
Steve Warby