Remove popup overlay from MHTML when requested

components/offline_pages/core/client_policy_controller.cc

Index: components/offline_pages/core/client_policy_controller.cc
diff --git a/components/offline_pages/core/client_policy_controller.cc b/components/offline_pages/core/client_policy_controller.cc
index c2db05186411b5d96974f87364d9400e21f298ce..aa9e4bf473d5dd9eecebb9ae91b3c4a70ac6e8ff 100644
--- a/components/offline_pages/core/client_policy_controller.cc
+++ b/components/offline_pages/core/client_policy_controller.cc
@@ -35,6 +35,7 @@ ClientPolicyController::ClientPolicyController() {
                                      kUnlimitedPages, kUnlimitedPages)
           .SetIsSupportedByDownload(true)
           .SetIsRemovedOnCacheReset(false)
+          .SetRemovePopupOverlay(true)
           .Build()));
   policies_.insert(std::make_pair(
       kCCTNamespace,
@@ -154,6 +155,11 @@ ClientPolicyController::GetNamespacesRestrictedToOriginalTab() const {
   return *show_in_original_tab_cache_;
 }
 
+bool ClientPolicyController::ShouldRemovePopupOverlay(
+    const std::string& name_space) const {
+  return GetPolicy(name_space).feature_policy.remove_popup_overlay;
+}
+
 void ClientPolicyController::AddPolicyForTest(
     const std::string& name_space,
     const OfflinePageClientPolicyBuilder& builder) {