This is a rather poor “port” (can’t really call it that at all IMO) of an Arduino library.
In order to make it work, you’d need to download the library sources via particle library view camera_VC0706, add new files to your Web IDE project, name them accordingly and copy the .h and .cpp files from the downloaded sources into your project.
Then you can replace all occurrences of SoftwareSerial with Serial1 (you won’t need ParticleSoftSerial when you use one of the HW interfaces present on the Electron) and repair any other errors you’ll find.
I did a quick’n’dirty “repair” here (it still throws a ton of warnings tho’)
https://go.particle.io/shared_apps/5fc2049ae6f0b000092cb085
(this link will be invalidated in a few days)