Add feature and flag for system media permissions info UI on Mac.

The UI will be added in a later CL, this just adds the feature to be used then.

Bug: 940893
Change-Id: I7656cb613bdb4a4c79f699ae2db840f73a775f5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1561103
Commit-Queue: Henrik Grunell <[email protected]>
Reviewed-by: Balazs Engedy <[email protected]>
Cr-Commit-Position: refs/heads/master@{#650223}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 0b93856..5906296 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3984,6 +3984,13 @@
      kOsAll,
      FEATURE_VALUE_TYPE(autofill::features::kAutofillCreditCardAuthentication)},
 
+#if defined(OS_MACOSX)
+    {"mac-system-media-permissions-info-ui",
+     flag_descriptions::kMacSystemMediaPermissionsInfoUiName,
+     flag_descriptions::kMacSystemMediaPermissionsInfoUiDescription, kOsMac,
+     FEATURE_VALUE_TYPE(features::kMacSystemMediaPermissionsInfoUi)},
+#endif  // defined(OS_MACOSX)
+
     // NOTE: Adding a new flag requires adding a corresponding entry to enum
     // "LoginCustomFlags" in tools/metrics/histograms/enums.xml. See "Flag
     // Histograms" in tools/metrics/histograms/README.md (run the