Remove popup overlay from MHTML when requested

components/offline_pages/core/offline_page_client_policy.h

Index: components/offline_pages/core/offline_page_client_policy.h
diff --git a/components/offline_pages/core/offline_page_client_policy.h b/components/offline_pages/core/offline_page_client_policy.h
index 79c3e916c3dae631c5bc3ac3e545aa09c401a54c..db4e6e93f7566f2b1bdd79be4f7a7d745383e245 100644
--- a/components/offline_pages/core/offline_page_client_policy.h
+++ b/components/offline_pages/core/offline_page_client_policy.h
@@ -55,12 +55,15 @@ struct FeaturePolicy {
   bool only_shown_in_original_tab;
   // Whether pages are removed on user-initiated cache reset. Defaults to true.
   bool is_removed_on_cache_reset;
+  // Whether to remove popup overlay that obstructs viewing normal content.
+  bool remove_popup_overlay;
 
   FeaturePolicy()
       : is_supported_by_download(false),
         is_supported_by_recent_tabs(false),
         only_shown_in_original_tab(false),
-        is_removed_on_cache_reset(true){};
+        is_removed_on_cache_reset(true),
+        remove_popup_overlay(false) {}
 };
 
 // The struct describing policies for various namespaces (Bookmark, Last-N etc.)
@@ -144,6 +147,12 @@ class OfflinePageClientPolicyBuilder {
     return *this;
   }
 
+  OfflinePageClientPolicyBuilder& SetRemovePopupOverlay(
+      const bool remove_popup_overlay) {
+    policy_.feature_policy.remove_popup_overlay = remove_popup_overlay;
+    return *this;
+  }
+
  private:
   OfflinePageClientPolicy policy_;