Info
Here is a simple and quick solution to get Cranberry's PhoneGap IAP plugin to work with Crosswalk and Google Play with the correct billing settings.
This solves the problem in google play saying:
"To add in-app products, you need to add the BILLING permission to your APK."
Step One
Update Construct 2 to version 185+. This is important because C2 185+ includes plugins and permissions needed in crosswalk for you and it will not work if you have an older version of C2.
Download and install cranberrys IAP app and put it in construct 2s plugin folder as usual:
Download IAP Plugin
Update link by @Carbincopy have fun and enjoy.
Step 2
1. Open your project in Construct 2 and insert the Phonegap IAP plugin into your project.
2. Create a new app in your Google Play Developer account and then copy your app license key.
3. Click on the Phonegap IAP plugin in your C2 projects object list and paste the key where is says "Android app application license key".
4. Export your project with the Android option and do not minify the script. I don't know if it matters but I didn't do that and it works :P So you can try both if you want.
Step 3
1. Open XDK and create a new project and import your C2 exported folder.
2. Fill out the build settings under "Android-Crosswalk" as usual and also the splash screen and icons if you want. Check the full screen option is always recommended.
3. Go to the build tab at the top and choose Crosswalk for Android option and upload your project to get your new settings.
4. BUILD!
5. Upload your brand new APK to your Google Play Developer account as an Alpha, Beta or Production.
6. When this is done, you should be able to click on "In-app Products" on your app in Google Play and add the products you want.
7. DONE!