Set prefs::kDefaultSearchProviderEnabled to false according to policy.

chrome/browser/policy/configuration_policy_handler.cc

Index: chrome/browser/policy/configuration_policy_handler.cc
diff --git a/chrome/browser/policy/configuration_policy_handler.cc b/chrome/browser/policy/configuration_policy_handler.cc
index b29c567fc7e229a2af986b6666bcafbd2992aeef..354abc179d21d596c00f5cb2fa68006537da720f 100644
--- a/chrome/browser/policy/configuration_policy_handler.cc
+++ b/chrome/browser/policy/configuration_policy_handler.cc
@@ -514,6 +514,8 @@ bool DefaultSearchPolicyHandler::CheckPolicySettings(const PolicyMap& policies,
 void DefaultSearchPolicyHandler::ApplyPolicySettings(const PolicyMap& policies,
                                                      PrefValueMap* prefs) {
   if (DefaultSearchProviderIsDisabled(policies)) {
+    prefs->SetBoolean(prefs::kDefaultSearchProviderEnabled, false);
+
     // If default search is disabled, the other fields are ignored.
     prefs->SetString(prefs::kDefaultSearchProviderName, std::string());
     prefs->SetString(prefs::kDefaultSearchProviderSearchURL, std::string());