[merchant trust] Add learn survey

Add learn survey config. The survey is shown when user clicks on a
button in "Merchant trust" page info subpage. If the survey cannot be
shown (for example, there was another survey in this milestone), the
button is not available.

Bug: 378854311
Change-Id: I10eeec7759dd058243a029fd68c620dc96b28e1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6191871
Reviewed-by: Nicola Tommasi <[email protected]>
Commit-Queue: Nicola Tommasi <[email protected]>
Reviewed-by: Martin Šrámek <[email protected]>
Auto-Submit: Olesia Marukhno <[email protected]>
Reviewed-by: Elly FJ <[email protected]>
Code-Coverage: [email protected] <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1412833}
diff --git a/components/page_info/core/features.cc b/components/page_info/core/features.cc
index d4883848..69018ff 100644
--- a/components/page_info/core/features.cc
+++ b/components/page_info/core/features.cc
@@ -116,4 +116,8 @@
         &kMerchantTrustEvaluationExperimentSurvey,
         "RequiredInteractionDuration", base::Seconds(5)};
 
+BASE_FEATURE(kMerchantTrustLearnSurvey,
+             "MerchantTrustLearnSurvey",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
 }  // namespace page_info