Autoplay notification should not be shown for local files

[srirambv]

Test Plan

1. Clean install the build
2. Open a mp4 file from local machine
3. Video should start playing and no auto play notification should be shown

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

• Describe the issue you encountered:
  Autoplay notification shown for local files instead of playing the video upload load

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

• Brave Version (revision SHA):
  Brave 0.15.304
  rev b872523
  Muon 3.0.103

• Steps to reproduce:

  1. Open a new tab and open a .mp4 file from machine
  2. Auto play notification is shown instead of playing the video automatically

• Actual result:
  Autoplay notification shown for local files

• Expected result:
  For local files loaded in browser there should not be any autoplay notification shown.

• 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?
  N/A

• Can this issue be consistently reproduced?
  Yes

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:
  

• Any related issues:
  cc: @darkdh