Reland "Separate Core Location flag into 2 flags for backend and permission UI"

This reverts commit 1787bd86d28c3f7d70c1cc5d8f43d6c1a1fec5be.

Reason for revert: Relanding with fix for flaky test.

Original change's description:
> Revert "Separate Core Location flag into 2 flags for backend and permission UI"
>
> This reverts commit cf5951ddec7a3565cbc6e825b6e459d7ebda161b.
>
> Reason for revert: Likely culprit for GeolocationServiceUnitTest.UrlWithApiKey flakiness on Mac
>
> Original change's description:
> > Separate Core Location flag into 2 flags for backend and permission UI
> >
> > The Permission UI for getting location permission from mac is completely
> > separate from the actual Core Location backend. Furthermore, once we
> > have location permission from macOS our Network Location Provider works
> > as intended. This CL separates those 2 independent workflows and allows
> > the Network Location Provider to monitor permission and act accordingly.
> >
> > Bug: 1112630
> > Change-Id: I4e3141f756eadcb3d7ecc66c347fc24148505edc
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2454307
> > Commit-Queue: James Hollyer <[email protected]>
> > Reviewed-by: Reilly Grant <[email protected]>
> > Cr-Commit-Position: refs/heads/master@{#821050}
>
> [email protected],[email protected]
>
> Change-Id: Icf38bfb889a62ee4e6d70eff0bc1adc2316d9ed6
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: 1112630
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2502368
> Reviewed-by: David Roger <[email protected]>
> Commit-Queue: David Roger <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#821178}

[email protected],[email protected],[email protected]

# Not skipping CQ checks because this is a reland.

Bug: 1112630
Change-Id: I5b8722879d719ef7c5ee4951caf6a4f6341747c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2504597
Reviewed-by: James Hollyer <[email protected]>
Reviewed-by: Reilly Grant <[email protected]>
Commit-Queue: James Hollyer <[email protected]>
Cr-Commit-Position: refs/heads/master@{#821593}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 5a08a20..6be6e19 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -5937,6 +5937,13 @@
 #endif
 
 #if defined(OS_MAC)
+    {"enable-core-location-backend",
+     flag_descriptions::kMacCoreLocationBackendName,
+     flag_descriptions::kMacCoreLocationBackendDescription, kOsMac,
+     FEATURE_VALUE_TYPE(features::kMacCoreLocationBackend)},
+#endif
+
+#if defined(OS_MAC)
     {"enable-core-location-implementation",
      flag_descriptions::kMacCoreLocationImplementationName,
      flag_descriptions::kMacCoreLocationImplementationDescription, kOsMac,