Implement EME UI

[cpeterso]

Why/User Benefit/User Problem

Users would like to watch YouTube EME content they have paid for.

What / Requirements

Summary of desired UI features:

1. "Play DRM-controlled content" setting to enable/disable EME in FFTV (like desktop Firefox).
2. DRM icon in the address bar and site info for pages that play EME content (like desktop Firefox).
3. User prompt offering to re-enable EME if the user tries to play EME content but they disabled the "Play DRM-controlled content" setting.

A draft of more detailed UI requirements: https://docs.google.com/document/d/1O7mPFSW2AO2MxWM1t3CwHrwPEJ7THxHjgXWUG74JBAc/edit#

NOTE: These UI features might not be possible to implement with Amazon's WebView! We will need to research whether WebView will allow us to detect and intercept EME playback so we can show a EME prompt and site info.

Acceptance Criteria (how do I know when I’m done?)

• Users can play YouTube EME content.
• Users can play Clear Key EME content on Google’s Shaka Player demo page.

[ghost]

Perhaps a more general question but might I ask why there has been no progress in milestones of this repo for 2 months?

Just asking because I don't know the development workflow here.

Keep up the good work!