XY coordinate for the new window when opening needs to offset slightly to make it easy to find multiple windows

[jenn-rhim]

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

• Describe the issue you encountered:
  New windows stack exactly the same position as the previous one obscuring the previous window

• Platform (Win7, 8, 10? macOS? Linux distro?):
  macOS 10.12.6

• Brave Version (revision SHA):
  0.18.29

• Steps to reproduce:

  1. Have an existing brave window
  2. Open a new window (Ctrl N)
  3. New window stacks right on top of the window below

• Actual result:
  New window stacks right on top of the window below, making it difficult to know that there is a window below and to get to the previous window, the user would have to move the top window out of the way before they can get to the one below.

• Expected result:
  Offset the xy coordinate of where the new window instance comes up

• 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?
  Yes

• Can this issue be consistently reproduced?
  Yes

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:
  
  

• Any related issues:

[NejcZdovc]

closing this as a dupe of #8925. This issue was fixed in 0.20.x with #10458