Disable motion sensors on desktop

[pes10k]

Test plan

See brave/brave-core#2802

Description

Currently Brave enables the motion sensor APIs by default

Brave blocks motion sensors on Android by default currently (https://github.com/brave/browser-android-tabs/issues/1669). Would be good to disable on desktop too by default. Most of the time it'll be a no-op, but would be relevant on some systems (e.g. tablets).

Low web compat risk since most other browsers don't support: https://caniuse.com/#search=sensor

[fmarier]

Looks like this is a trivial fix: https://github.com/bromite/bromite/blob/master/build/patches/disable-sensors-access-site-setting-by-default.patch

See bromite/bromite#319.

[bsclifton]

Re-opening after brave/brave-core#2802 was reverted with brave/brave-core#3517

[btlechowski]

Verification passed on

Brave	0.72.110 Chromium: 78.0.3904.70 (Official Build) dev (64-bit)
Revision	edb9c9f3de0247fd912a77b7f6cae7447f6d3ad5-refs/branch-heads/3904@{#800}
OS	Ubuntu 18.04 LTS

Verified test plan from brave/brave-core#2802

Verified that Motion Sensors are off by default on clean profile and upgrade from 0.70.x

Verified passed with

Brave	0.72.110 Chromium: 78.0.3904.70 (Official Build) dev (64-bit)
Revision	edb9c9f3de0247fd912a77b7f6cae7447f6d3ad5-refs/branch-heads/3904@{#800}
OS	macOS Version 10.13.6 (Build 17G5019)

• Verified test plan from Disable motion sensors and background sync by default brave-core#2802

Verification passed on

Brave	1.1.1 Chromium: 78.0.3904.97 (Official Build) beta (64-bit)
Revision	021b9028c246d820be17a10e5b393ee90f41375e-refs/branch-heads/3904@{#859}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified test plan from Disable motion sensors and background sync by default brave-core#2802
  
  
  Verified that Motion Sensors are off by default on clean profile and upgrade from 0.70.x