Tab Label Rendering Issue

[jonathansampson]

Test plan

#10691 (comment)

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• Did you search for similar issues before submitting this one?
  Yes

• Describe the issue you encountered:
  Tab labels have an issue with rendering where previous values may not be cleared properly. As a result, this can paint two labels in the place of one.

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Desktop (Windows?)

• Brave Version (revision SHA):
  0.16.9

• Steps to reproduce:
  TBD

• Actual result:
  Labels become unreadable.

• Expected result:
  Labels remain legible and clear.

• Will the steps above reproduce in a fresh profile? If not what other info can be added?

• Is this an issue in the currently released version?
  Yes

• Can this issue be consistently reproduced?
  Yes

• Screenshot if needed:

[bsclifton]

cc: @cezaraugusto @luixxiul

[jonathansampson]

I believe this is related to the general tab-rendering issue where labels are made up of transparent text, masking a gradient background. We need to move to using a pseudo-element to achieve the fade effect. This requires a little work considering we need to accommodate hovered, non-hovered, theme colors, non-theme colors, private tabs, and public tabs.

[bsclifton]

@jonathansampson IIRC, these issues would also be resolved with that same fix:

• Tabs No Longer Show Full-Color Emoji Tabs No Longer Show Full-Color Emoji #8414
• Tab title often isn't updated until the cursor is moved over it or tab focus is changed Tab title often isn't updated until the cursor is moved over it or tab focus is changed #7765

[jonathansampson]

@bsclifton I believe that is correct.

[cezaraugusto]

@jonathansampson isn't this related to the improvement we talked last Sunday? if so I think you are very close btw.

++ for @bsclifton findings. If above is true I agree they'll be fixed by too.

[jonathansampson]

@cezaraugusto It is. I should have that wrapped up very soon.