WebVR loop is not correcly paused in Android

[MortimerGoro]

Hardware

I tested it on Oculus but can happen on more platforms

Steps to Reproduce

• Add a console.log to a WebVR sample raf
• Move the app to the background or close the app
• The logs still shows in the console at a high refresh rate.

Current Behavior

WebGL RAF still runs when the aplicattion is paused or closed. This will drain the device battery.

Expected Behavior

WebGL RAF must stop when the app is paused or closed.

Possible Solution

I tried the same test on the GeckoView example app and the WebGL RAF logs are paused correctly. So this seems related to VRDisplay.raf event loop.

[MortimerGoro]

This is an important issue because it can totally drain the battery of the device while not using the app cc @jvonitter @philip-lamb

[MortimerGoro]

I created two Gecko patches to fix this issue:

• https://bugzilla.mozilla.org/show_bug.cgi?id=1570383
• https://bugzilla.mozilla.org/show_bug.cgi?id=1570671

[MortimerGoro]

Required patches landed in #1508