Chrome Packaged App: Retrieving FileEntry in Dart from command line (LaunchData) parameter - file

Question

Similarly to another post on this topic, I've been attempting to run my app from the command line with the file path of a local XML file so that my main.dart can parse this file in order to extract information relevant to program operation from it. I've been stumped as to how to appropriately access the FileEntry reference included in launchData -- the parameter for the onLaunched event.
Here's what I currently have:
manifest.json:
...
"permissions": [
"storage",
"fileSystem",
"*://*/*"
],
"file_handlers" : {
"any" : {
"types" : [ "*" ]
}
},
...
background.js:
chrome.app.runtime.onLaunched.addListener(function(launchData) {
chrome.app.window.create(
'htmlFile.html',
{...},
function(createdWindow) {
createdWindow.contentWindow.launchData = launchData;
});
});
At this point, I can't access launchData from main.dart because trying to do
FileEntry entry = (chrome.app.window.current().contentWindow.launchData as chrome.LaunchData).items.elementAt(0).entry;
to get the FileEntry results in an error for accessing launchData. I'm really confused about how I'm supposed to access the FileEntry that I want from my Dart code as a result.

Answer 1

I ended up with this as my solution:
manifest.json:
...
"file_handlers": {
"any": {
"extensions": [
"xml"
]
}
},
...
background.js:
chrome.app.runtime.onLaunched.addListener(function(launchData) {
chrome.app.window.create(
'htmlSource.html',
{
id: 'mainWindow',
state: "fullscreen"
},
function(createdWindow) {
if(launchData.items !== undefined) {
launchData.items[0].entry.file(
function(result) {
var reader = new FileReader();
var XML;
reader.onloadend = function(){
XML = reader.result;
chrome.storage.local.set({'XML': XML});
};
reader.readAsText(result);
},
function(){
console.log("Error reading XML file");
}
);
} else {
console.log("No file was detected.");
}
});
});
The dart code to retrieve the XML was simply:
String text = (await chrome.storage.local.get('XML'))['XML'];