Check if we can use Google Earth plugin

gistfile1.js

//Check if Google API script is installed and
//check if Google Earth namespaace is there
if(!google || !google.earth){
	return false;
}
//Check if plugin is supported or installed
if(!google.earth.isSupported() || !google.earth.isInstalled()){
	return false;
}
//We can use it
return true;