A pdf file can show up in an iframe in Chrome, but not in IE.
we have no control over what the users of our public website have installed, and we can't ask them to install an add-in or configure their settings.
What we need is a server-end solution, that takes a pdf and renders it on the screen in ANY browser, including IE. I don't care if it renders the pdf as an image or as html or anything else for that matter, as long as it works.
It doesn't have to be free.
The chosen answer led me to discover pdf.js. Viewer js is based on pdf.js, but it has some limitations that its base does not have. I needed to load pdfs from other domains and also load base64 encoded pdf data. pdf.js enabled me to do that. The chosen answer led me in the right direction.