Setting frameData.pose (/w Origin Trial)

[benfoxall]

I'm absolutely sure that this is covered by #21, though I thought it might be useful to log a specific example of Origin Trial issues.

When viewing a page with an active webvr origin-trial, I get the following error:

TypeError: Cannot assign to read only property 'pose' of object '#<VRFrameData>'

It looks like I'm passing a native VRFrameData object which has a readonly pose attribute

[spite]

Yes, that's basically the issue, VRFrameData gets "nativised" after the page has loaded.

I've tried a few workarounds, and I don't really like none because they're mean guaranteed breakage at some point, and I don't want to be troubleshooting full time. The current solution i have in dev, for instance, doesn't work with your page. So yay.

To be honest, it's kind of annoying having to re-architect everything just because the combined hack of extensions injection and origin-trial enhancement.

For now I rather developers be able to use the emulator -since they can work without enabling the origin-trial- and inconvenience the users that access origin-trial sites since, well, they didn't have a VR device to begin with.

EDIT: it doesn't help either knowing that this is going to change, and rewriting the extension now doesn't exclude having to rewrite yet again in a few weeks.

[spite]

I think the only real option is to wait for the page to query for devices, and then start the API replacement…

[sompylasar]

I've got this TypeError: Cannot assign to read only property 'pose' of object '#<VRFrameData>' at https://threejs.org/examples/webvr_cubes.html with chrome://flags/#enable-webvr disabled (and a fresh launch of Chrome). What am I doing wrong?

Google Chrome	61.0.3163.100 (Official Build) (64-bit)
Revision	57c9d07b416b5a2ea23d28247300e4af36329bdc-refs/branch-heads/3163@{#1250}
OS	Mac OS X
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Flash	27.0.0.183 /Users/ivanbabak/Library/Application Support/Google/Chrome/PepperFlash/27.0.0.183/PepperFlashPlayer.plugin
User Agent	Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36
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