Why is Chrome in Windows 7 Displaying Video Differently?

Man, I love this forum. Thank you Tom and Karsten. Karsten, that tutorial was very enlightening. I've obviously been breaking the law with my super-white levels, and while some browsers can handle it, Chrome in Windows 7 gamma-corrects the whole video, resulting in my 100-level whites being reduced to grey.

So now I need to figure out a workflow for creating my infinite white background. I can't just boost my highlights to 100 (instead of 120), because the white backdrop in my footage isn't completely uniform--there are subtle differences in brightness due to somewhat uneven lighting, which results in patches of grey. I need to completely over-expose the backdrop in order to get uniform white.

Here's my solution--tell me if you think this will work. I jack up my highlights so that the whole background is at least 100 (and much of it is illegal). But then I apply the Broadcast Safe effect to bring the values back to 100, effectively doing the same thing that a limiter does in audio production (which I'm more familiar with). Now since FCPX applies color correction AFTER effects are applied, I need to either create a compound clip first, or, it sounds like a less cumbersome approach is to add an adjustment layer and apply the Broadcast Safe effect to it.

I downloaded RT Adjustment Layer Title, and it appears to work. The video looks good in FCPX. However, I'm concerned that in the vector scope, the background values don't appear as uniform as in my generated white background--it seems to occupy around 99-100 instead of being uniformly 100. Attached is a screen shot.

I'm currently uploading a test video to YouTube to see how things look in Win7 Chrome browser, but am curious you think I should seek another solution, a harder limiter so to speak, that will bring the footage background to a uniform 100 value.

Shoot. I uploaded a broadcast-safe version of the video to YouTube and tested it in Windows 7 chrome browser and got the same grey background problem that I had originally. What else could possibly be causing this?

One thing that doesn't make sense to me is, if there is gamma correction being applied to the video that darkens the white background, wouldn't my black shirt appear darker too, instead of lighter?

A gamma curve effects the whole image, lifted by the mids and will effect everything except pure black, which your jacket isn't.

OK, if it's a curve then that makes sense. The highs are cut, but the mids are boosted.

but has the white of your mask the same color as the white of your bg?

Good question. I used to create masks by doing Generator-->Solids-->Whites and then selecting "Bright White" in the Generator tab of the inspector. But the mask in question was created in Motion so that I could create my own generator and eliminate a step (I'm making lots of videos). I'm trying another test video right now using the old generator workflow instead of the motion-created generator to see if I screwed something up (it's the only time I've ever used Motion).

But back to your question--how do I tell if the white of my mask is the same color? As you can see from the waveform screenshot above, even after applying "Broadcast Safe" to project, the background of my footage gives different results than the mask. So there is something different about it according to the scope.

Incidentally, it appears that others have identified this different way of Chrome treating whites:

https://www.youtube.com/watch?v=FXoilak-M7M

https://productforums.google.com/forum/#!topic/chrome/uWwb_2xRItU

However, I don't see a solution anywhere.