Tab preview animation on Windows 7 and Windows 10

[luixxiul]

Test plan

1. Launch Brave on Windows and open a few tabs
2. Ensure tab preview is enabled
3. Use mouse to do a tab preview
4. Confirm animation takes place while doing the preview (it should gradually fade in)

Original issue description

Describe the issue you encountered: Tab preview animation seems to be not working properly on Windows 7. It shows the preview on hover. Tested on VM.

Expected behavior:

• Platform (Win7, 8, 10? macOS? Linux distro?): Windows 7
• Brave Version: 0.11.2 Beta2
• Steps to reproduce:
  1.
  2.
  3.
• Screenshot if needed:
• Any related issues: Manual tests for Win-x64 0.11.2 Beta2 #2862

[srirambv]

Tested on Desktop running Windows 7 Prof. There is a very little blur effect in tab preview but not as prominent as in VM.

[luixxiul]

This can be reproduced on Win10 VM. Maybe this should be labelled wontfix.

[cezaraugusto]

Confused here. Did you tested after #2817 being merged? What should be the expected result?

[luixxiul]

@cezaraugusto I tested it on 0.11.2 Beta2 and think it has been merged. The problem I think is that when I hover the tab preview is displayed at that moment, and then, the tab starts brightening and darkening.

[cezaraugusto]

I had to change transitions to fix the flickering tab issue, maybe it's what you're seeing. Needs a little polish tho. I'll check with Brad how can we improve it.

[bradleyrichter]

@cezaraugusto your last video looked much smoother. Strange.

Basically, the tabs are not cross-fading. At one point you had them crossfading with the active tab showing in the middle of the sequence.

I was not able to preview any of your changes after that feedback.

There may be a problem in the structure that prevents the above approach?

[cezaraugusto]

@bradleyrichter it's like we talked on chat. :)

Assigning it to myself until I polish tab transitions.

[srirambv]

Verified on Windows x64

• 0.22.6 e6ff4ea
• libchromiumcontent: 65.0.3325.162
• muon: 5.1.0