about:blank shows chrome-extension in navigation button history

[srirambv]

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

Describe the issue you encountered:
about:blank shows chrome-extension in navigation button history

Expected behavior:
Should show about:blank similar to other about pages

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Windows 10 x64

• Brave Version:
  0.12.10 RC1

• Steps to reproduce:

  1. Set new tab opens with my homepage
  2. Clear the homepage field
  3. Open a new tab which shows about:blank navigate to a site and long press the back navigation button, shows full chrome extension for about:blank

• Screenshot if needed:
  

• Any related issues:
  Make empty home page address to be about:blank #5654
  cc: @cezaraugusto
  Setting milestone as 0.12.11, please change if required

#5657

[luixxiul]

Test plan: #5782 (comment)