Generate the limited entropy randomization source for eligible clients.

Bug: b/319690282
Change-Id: If5eec365c05014fee5dd055e2d9fd7ec64a72c82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5234953
Reviewed-by: Nate Fischer <[email protected]>
Commit-Queue: Yulun Zeng <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1254074}
diff --git a/components/variations/variations_test_utils.cc b/components/variations/variations_test_utils.cc
index 862e58f1..c13d55f 100644
--- a/components/variations/variations_test_utils.cc
+++ b/components/variations/variations_test_utils.cc
@@ -314,11 +314,14 @@
   return client_state;
 }
 
+// Constructs mocked EntropyProviders.
 MockEntropyProviders::MockEntropyProviders(
     MockEntropyProviders::Results results,
     uint32_t low_entropy_domain)
     : EntropyProviders(results.high_entropy.has_value() ? "client_id" : "",
-                       {0, low_entropy_domain}),
+                       {0, low_entropy_domain},
+                       // Use a non-empty value for test coverage.
+                       "limited_entropy_randomization_source"),
       low_provider_(results.low_entropy),
       high_provider_(results.high_entropy.value_or(0)) {}