Support OS location service on macOS

[simonhong]

Upstream already has CoreLocationProvider.
However, it doesn't work if Brave is not inserted in allowed list of Location Service.
If Brave is not inserted, we should use NetworkLocationProvider as a fallback

On Windows, if user doesn't enable OS location service, NetworkLocationProvider is set even if LocationProviderWinrt flag is on. However, NetworkLocationProvider is not used on macOS as a fallback.

STR:

1. Check MacCoreLocationBackendStudy is enabled from brave://version
2. Load https://www.gps-coordinates.net/my-location
3. Allow location permission via site settings bubble below

4. Allow Brave browser for accessing os location via `Preferences`

5. Reload and check it shows correct location

[simonhong]

It seems macOS support is in-progress and it's targeted to C86
Upstream issue - https://bugs.chromium.org/p/chromium/issues/detail?id=1051591
I think it's fine to wait upstream progress. WDYT? @bsclifton @rebron @fmarier

[bsclifton]

@simonhong SGTM 👍

[rebron]

Possibly fixed with CR87 with https://chromium.googlesource.com/chromium/src.git/+/38a2229ca75e9cb1e1a17acc6c29027c302a0ba4

[rebron]

cc: @mihaiplesa @mkarolin

[simonhong]

I think we can fix this by enabling Core Location Backend feature by default?

[simonhong]

Set 1.27.x milestone as MacCoreLocationBackendStudy is also applied to current release channel.
I can see MacCoreLocationBackendStudy is enabled via brave://version like below and can get accurate location.
STR is added in the description.
cc @kjozwiak @rebron

[LaurenWags]

Verified passed with

Brave | 1.27.110 Chromium: 92.0.4515.131 (Official Build) (x86_64)
-- | --
Revision | 6b8d6c56ce21e38a72f7c4becb5abc1fa5134f29-refs/branch-heads/4515@{#1933}
OS | macOS Version 10.15.7 (Build 19H1217)

Confirmed MacCoreLocationBackendStudy:Enabled on brave://version.
Confirmed prompted to select location permission preference via site settings bubble.
Confirmed selecting Block button did not prompt me to allow Brave Browser to access OS location services via Preferences.
Confirmed selecting Allow button did prompt me to allow Brave Browser to access OS location services via Preferences.
Confirmed after allowing Brave Browser to use the macOS Location Services and refreshing the https://www.gps-coordinates.net/my-location page, the map showed my correct location.

Example	Example	Example

---

Verified passed with

Brave	1.27.110 Chromium: 92.0.4515.131 (Official Build) (arm64)
Revision	6b8d6c56ce21e38a72f7c4becb5abc1fa5134f29-refs/branch-heads/4515@{#1933}
OS	macOS Version 11.5.1 (Build 20G80)

Confirmed MacCoreLocationBackendStudy:Enabled on brave://version.
Confirmed prompted to select location permission preference via site settings bubble.
Confirmed selecting Block button did not prompt me to allow Brave Browser to access OS location services via Preferences.
Confirmed selecting Allow button did prompt me to allow Brave Browser to access OS location services via Preferences.
Confirmed after allowing Brave Browser to use the macOS Location Services and refreshing the https://www.gps-coordinates.net/my-location page, the map showed my correct location.

Example	Example	Example

---

Verified PASSED using

Brave	1.27.110 Chromium: 92.0.4515.131 (Official Build) (x86_64)
Revision	6b8d6c56ce21e38a72f7c4becb5abc1fa5134f29-refs/branch-heads/4515@{#1933}
OS	macOS Version 11.5.1 (Build 20G80)

Confirmed MacCoreLocationBackendStudy:Enabled on brave://version.
Confirmed prompted to select location permission preference via site settings bubble.
Confirmed selecting Block button did not prompt me to allow Brave Browser to access OS location services via Preferences.
Confirmed selecting Allow button did prompt me to allow Brave Browser to access OS location services via Preferences.
Confirmed after allowing Brave Browser to use the macOS Location Services and refreshing the https://www.gps-coordinates.net/my-location page, the map showed my correct location.

Example	Example	Example

[kjozwiak]

Going to exclude this from the notes as this already went out via Griffin. This was more of a double check to make sure things are working as expected.