Pref change restart doesn't launch the browser again

[srirambv]

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

• Describe the issue you encountered:
  Pref change restart doesn't launch the browser again

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

• Brave Version (revision SHA):
  Brave 0.14.0
  rev ffa6f8f

• Steps to reproduce:

  1. Do a clean install/upgrade to 0.14.0 Preview 5
  2. Change pref options which require browser restart
  3. All process gets killed and browser doesn't restart, have to manually restart it

• Actual result:
  Pref change restart doesn't launch the browser again

• Expected result:
  Should restart the browser when user clicks yes to restart browser

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

• Is this an issue in the currently released version?
  No

• Can this issue be consistently reproduced?
  Yes

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:
  

• Any related issues:
  Pref change restart doesn't relaunch the browser #5938

[bsclifton]

confirmed on Windows and macOS; command line is showing:

[2940:775:0326/230201.806129:ERROR:relauncher.cc(178)] failed to launch program
process exited with code 0

It may / may not be related to brave/muon@f2925f7#diff-a2a29fbd6a5f9747649d3c2c444dae3fL97

[bsclifton]

Assigned to @bridiver as he is fixing some issues related to relauncher