Add a kill switch for all of Web Bluetooth.

chrome/browser/permissions/permission_context_base.h

Index: chrome/browser/permissions/permission_context_base.h
diff --git a/chrome/browser/permissions/permission_context_base.h b/chrome/browser/permissions/permission_context_base.h
index 6c70c6c86abd8d7a028bfc6a3779df7c998bc784..3a89a04097aa0f079a180636bf68c15c28a7d3bb 100644
--- a/chrome/browser/permissions/permission_context_base.h
+++ b/chrome/browser/permissions/permission_context_base.h
@@ -62,11 +62,13 @@ class PermissionContextBase : public KeyedService {
   ~PermissionContextBase() override;
 
   // A field trial used to enable the global permissions kill switch.
-  // This is public for testing purposes.
+  // This is public so permissions that don't yet inherit from
+  // PermissionContextBase can use it.
   static const char kPermissionsKillSwitchFieldStudy[];
 
   // The field trial param to enable the global permissions kill switch.
-  // This is public for testing purposes.
+  // This is public so permissions that don't yet inherit from
+  // PermissionContextBase can use it.
   static const char kPermissionsKillSwitchBlockedValue[];
 
   // The renderer is requesting permission to push messages.