[iOS] Adjust supervised user interstitial font size from iOS settings

This CL allows the "Ask your parent" interstitial to adjust to iOS system text size. "Zoom text..." from 3-dot menu will still work on
top of this.

Based on components/security_interstitials/.../interstitial_large.html

Bug: 405993406
Change-Id: I26c3e0135428fa38b8b692484198252ff97f7eb9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6395058
Commit-Queue: Duong Dac <ddac@chromium.org>
Reviewed-by: Carlos IL <carlosil@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1439803}

chrome/browser/ui/webui/interstitials/interstitial_ui.cc

@@ -5,6 +5,7 @@
 #include "chrome/browser/ui/webui/interstitials/interstitial_ui.h"
 
 #include <memory>
+#include <optional>
 #include <utility>
 
 #include "base/atomic_sequence_num.h"
@@ -734,5 +735,5 @@ std::string InterstitialHTMLSource::GetSupervisedUserInterstitialHTML(
       allow_access_requests, first_custodian, second_custodian, reason,
       g_browser_process->GetApplicationLocale(),
       /*already_sent_remote_request=*/false,
-      /*is_main_frame=*/true);
+      /*is_main_frame=*/true, /*ios_font_size_multiplier=*/std::nullopt);
 }

components/security_interstitials/core/BUILD.gn

@@ -36,6 +36,8 @@ static_library("core") {
     "ssl_error_ui.h",
     "urls.cc",
     "urls.h",
+    "utils.cc",
+    "utils.h",
   ]
 
   if (!is_ios) {

components/security_interstitials/core/utils.cc

@@ -0,0 +1,27 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/security_interstitials/core/utils.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+
+namespace security_interstitials {
+
+void AdjustFontSize(base::Value::Dict& load_time_data,
+                    float font_size_multiplier) {
+  std::string* value = load_time_data.FindString("fontsize");
+  CHECK(value);
+  std::string old_size = *value;
+  // `old_size` should be in form of "75%".
+  CHECK(old_size.size() > 1 && old_size.back() == '%');
+  double new_size = 75.0;
+  bool converted =
+      base::StringToDouble(old_size.substr(0, old_size.size() - 1), &new_size);
+  CHECK(converted);
+  new_size *= font_size_multiplier;
+  load_time_data.Set("fontsize", base::StringPrintf("%.0lf%%", new_size));
+}
+
+}  // namespace security_interstitials

components/security_interstitials/core/utils.h

@@ -0,0 +1,19 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_SECURITY_INTERSTITIALS_CORE_UTILS_H_
+#define COMPONENTS_SECURITY_INTERSTITIALS_CORE_UTILS_H_
+
+#include "base/values.h"
+
+namespace security_interstitials {
+
+// Adjusts the interstitial page's template parameter "fontsize" by the font
+// size multiplier.
+void AdjustFontSize(base::Value::Dict& load_time_data,
+                    float font_size_multiplier);
+
+}  // namespace security_interstitials
+
+#endif  // COMPONENTS_SECURITY_INTERSTITIALS_CORE_UTILS_H_

components/supervised_user/DEPS

@@ -10,6 +10,7 @@ include_rules = [
   "+components/prefs",
   "+components/pref_registry",
   "+components/safe_search_api",
+  "+components/security_interstitials/core",
   "+components/strings/grit",
   "+components/signin",
   "+components/sync",

components/supervised_user/core/browser/BUILD.gn

@@ -125,6 +125,7 @@ static_library("browser") {
     "//components/google/core/common",
     "//components/prefs",
     "//components/resources:components_resources",
+    "//components/security_interstitials/core",
     "//components/signin/internal/identity_manager",
     "//components/signin/public/base",
     "//components/signin/public/identity_manager",

components/supervised_user/core/browser/resources/supervised_user_block_interstitial_v3.html

@@ -14,7 +14,7 @@
   <script src="%ROOT_GEN_DIR%/components/supervised_user/core/browser/resources/minified/supervised_user_block_interstitial_v3.js"></script>
 </if>
 </head>
-<body class="supervised-user-block">
+<body class="supervised-user-block" <if expr="is_ios">style="font-size: $i18n{fontsize}"</if>>
 <div class="frame-blocked" id="frame-blocked" tabindex="-1">
   <div class="message-container">
     <picture id="error-page-illustration">

components/supervised_user/core/browser/supervised_user_error_page.cc

@@ -12,6 +12,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "components/grit/components_resources.h"
+#include "components/security_interstitials/core/utils.h"
 #include "components/signin/public/base/avatar_icon_util.h"
 #include "components/strings/grit/components_strings.h"
 #include "components/supervised_user/core/browser/supervised_user_service.h"
@@ -78,50 +79,54 @@ std::string BuildErrorPageHtml(bool allow_access_requests,
                                FilteringBehaviorReason reason,
                                const std::string& app_locale,
                                bool already_sent_remote_request,
-                               bool is_main_frame) {
-  base::Value::Dict strings;
-  strings.Set("blockPageTitle",
-              l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_TITLE));
-  strings.Set("allowAccessRequests", allow_access_requests);
+                               bool is_main_frame,
+                               std::optional<float> ios_font_size_multiplier) {
+  base::Value::Dict load_time_data;
+  load_time_data.Set("blockPageTitle",
+                     l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_TITLE));
+  load_time_data.Set("allowAccessRequests", allow_access_requests);
 
   if (custodian.has_value()) {
-    strings.Set("custodianName", custodian->GetName());
-    strings.Set("custodianEmail", custodian->GetEmailAddress());
-    strings.Set(
+    load_time_data.Set("custodianName", custodian->GetName());
+    load_time_data.Set("custodianEmail", custodian->GetEmailAddress());
+    load_time_data.Set(
         "avatarURL1x",
         BuildAvatarImageUrl(custodian->GetProfileImageUrl(), kAvatarSize1x));
-    strings.Set(
+    load_time_data.Set(
         "avatarURL2x",
         BuildAvatarImageUrl(custodian->GetProfileImageUrl(), kAvatarSize2x));
   } else {
     // empty custodianName denotes no custodian, see
     // components/supervised_user/core/browser/resources/supervised_user_block_interstitial_v2.js
-    strings.Set("custodianName", "");
+    load_time_data.Set("custodianName", "");
   }
 
   if (second_custodian.has_value()) {
-    strings.Set("secondCustodianName", second_custodian->GetName());
-    strings.Set("secondCustodianEmail", second_custodian->GetEmailAddress());
-    strings.Set("secondAvatarURL1x",
-                BuildAvatarImageUrl(second_custodian->GetProfileImageUrl(),
-                                    kAvatarSize1x));
-    strings.Set("secondAvatarURL2x",
-                BuildAvatarImageUrl(second_custodian->GetProfileImageUrl(),
-                                    kAvatarSize2x));
+    load_time_data.Set("secondCustodianName", second_custodian->GetName());
+    load_time_data.Set("secondCustodianEmail",
+                       second_custodian->GetEmailAddress());
+    load_time_data.Set(
+        "secondAvatarURL1x",
+        BuildAvatarImageUrl(second_custodian->GetProfileImageUrl(),
+                            kAvatarSize1x));
+    load_time_data.Set(
+        "secondAvatarURL2x",
+        BuildAvatarImageUrl(second_custodian->GetProfileImageUrl(),
+                            kAvatarSize2x));
   } else {
     // empty secondCustodianName denotes no second custodian, see
     // components/supervised_user/core/browser/resources/supervised_user_block_interstitial_v2.js
-    strings.Set("secondCustodianName", "");
+    load_time_data.Set("secondCustodianName", "");
   }
 
-  strings.Set("alreadySentRemoteRequest", already_sent_remote_request);
-  strings.Set("isMainFrame", is_main_frame);
+  load_time_data.Set("alreadySentRemoteRequest", already_sent_remote_request);
+  load_time_data.Set("isMainFrame", is_main_frame);
 
   bool local_web_approvals_enabled =
       (is_main_frame && supervised_user::IsLocalWebApprovalsEnabled()) ||
       (!is_main_frame &&
        supervised_user::IsLocalWebApprovalsEnabledForSubframes());
-  strings.Set("isLocalWebApprovalsEnabled", local_web_approvals_enabled);
+  load_time_data.Set("isLocalWebApprovalsEnabled", local_web_approvals_enabled);
 
   std::string block_page_header;
   std::string block_page_message;
@@ -135,36 +140,41 @@ std::string BuildErrorPageHtml(bool allow_access_requests,
         IDS_BLOCK_INTERSTITIAL_HEADER_ACCESS_REQUESTS_DISABLED);
   }
 
-  strings.Set("blockPageHeader", block_page_header);
-  strings.Set("blockPageMessage", block_page_message);
+  load_time_data.Set("blockPageHeader", block_page_header);
+  load_time_data.Set("blockPageMessage", block_page_message);
 
   if (!supervised_user::IsBlockInterstitialV3Enabled()) {
     // For the V2 interstitial, the filtering reason is displayed in a
     // separate UI component.
-    strings.Set("blockReasonMessage",
-                l10n_util::GetStringUTF8(GetBlockMessageID(
-                    reason, /*single_parent=*/!second_custodian.has_value())));
-    strings.Set("blockReasonHeader",
-                l10n_util::GetStringUTF8(IDS_SUPERVISED_USER_BLOCK_HEADER));
-    strings.Set("siteBlockHeader",
-                l10n_util::GetStringUTF8(IDS_GENERIC_SITE_BLOCK_HEADER));
-    strings.Set("showDetailsLink",
-                l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_SHOW_DETAILS));
-    strings.Set("hideDetailsLink",
-                l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_HIDE_DETAILS));
+    load_time_data.Set(
+        "blockReasonMessage",
+        l10n_util::GetStringUTF8(GetBlockMessageID(
+            reason, /*single_parent=*/!second_custodian.has_value())));
+    load_time_data.Set(
+        "blockReasonHeader",
+        l10n_util::GetStringUTF8(IDS_SUPERVISED_USER_BLOCK_HEADER));
+    load_time_data.Set("siteBlockHeader",
+                       l10n_util::GetStringUTF8(IDS_GENERIC_SITE_BLOCK_HEADER));
+    load_time_data.Set(
+        "showDetailsLink",
+        l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_SHOW_DETAILS));
+    load_time_data.Set(
+        "hideDetailsLink",
+        l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_HIDE_DETAILS));
   }
 
-  strings.Set(
+  load_time_data.Set(
       "remoteApprovalsButton",
       l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_ASK_IN_A_MESSAGE_BUTTON));
-  strings.Set("backButton", l10n_util::GetStringUTF8(IDS_REQUEST_SENT_OK));
+  load_time_data.Set("backButton",
+                     l10n_util::GetStringUTF8(IDS_REQUEST_SENT_OK));
 
-  strings.Set(
+  load_time_data.Set(
       "localApprovalsButton",
       l10n_util::GetStringUTF8(IDS_BLOCK_INTERSTITIAL_ASK_IN_PERSON_BUTTON));
-  strings.Set("localApprovalsRemoteRequestSentButton",
-              l10n_util::GetStringUTF8(
-                  IDS_BLOCK_INTERSTITIAL_ASK_IN_PERSON_INSTEAD_BUTTON));
+  load_time_data.Set("localApprovalsRemoteRequestSentButton",
+                     l10n_util::GetStringUTF8(
+                         IDS_BLOCK_INTERSTITIAL_ASK_IN_PERSON_INSTEAD_BUTTON));
 
   std::string request_sent_message;
   std::string request_failed_message;
@@ -180,17 +190,24 @@ std::string BuildErrorPageHtml(bool allow_access_requests,
           ? IDS_CHILD_BLOCK_INTERSTITIAL_REQUEST_FAILED_MESSAGE_SINGLE_PARENT
           : IDS_CHILD_BLOCK_INTERSTITIAL_REQUEST_FAILED_MESSAGE_MULTI_PARENT);
 
-  strings.Set("requestSentMessage", std::move(request_sent_message));
-  strings.Set("requestSentDescription", std::move(request_sent_description));
-  strings.Set("requestFailedMessage", std::move(request_failed_message));
-  webui::SetLoadTimeDataDefaults(app_locale, &strings);
+  load_time_data.Set("requestSentMessage", std::move(request_sent_message));
+  load_time_data.Set("requestSentDescription",
+                     std::move(request_sent_description));
+  load_time_data.Set("requestFailedMessage", std::move(request_failed_message));
+  webui::SetLoadTimeDataDefaults(app_locale, &load_time_data);
+
+  if (ios_font_size_multiplier) {
+    security_interstitials::AdjustFontSize(load_time_data,
+                                           ios_font_size_multiplier.value());
+  }
+
   std::string html =
       ui::ResourceBundle::GetSharedInstance().LoadDataResourceString(
           supervised_user::IsBlockInterstitialV3Enabled()
               ? IDR_SUPERVISED_USER_BLOCK_INTERSTITIAL_V3_HTML
               : IDR_SUPERVISED_USER_BLOCK_INTERSTITIAL_V2_HTML);
   webui::AppendWebUiCssTextDefaults(&html);
-  std::string error_html = webui::GetI18nTemplateHtml(html, strings);
+  std::string error_html = webui::GetI18nTemplateHtml(html, load_time_data);
   return error_html;
 }
 

components/supervised_user/core/browser/supervised_user_error_page.h

@@ -22,7 +22,8 @@ std::string BuildErrorPageHtml(bool allow_access_requests,
                                FilteringBehaviorReason reason,
                                const std::string& app_locale,
                                bool already_sent_remote_request,
-                               bool is_main_frame);
+                               bool is_main_frame,
+                               std::optional<float> ios_font_size_multiplier);
 
 }  //  namespace supervised_user
 

components/supervised_user/core/browser/supervised_user_error_page_unittest.cc

@@ -4,6 +4,8 @@
 
 #include "components/supervised_user/core/browser/supervised_user_error_page.h"
 
+#include <optional>
+
 #include "base/memory/raw_ptr_exclusion.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
@@ -195,7 +197,8 @@ TEST_P(SupervisedUserErrorPageTest_BuildHtml, BuildHtml) {
       param.allow_access_requests, param.custodian, param.second_custodian,
       param.reason,
       /*app_locale=*/"",
-      /*already_sent_remote_request=*/false, /*is_main_frame=*/true);
+      /*already_sent_remote_request=*/false, /*is_main_frame=*/true,
+      /*ios_font_size_multiplier=*/std::nullopt);
 
   VerifyCustodianInfo();
 

components/supervised_user/core/browser/supervised_user_interstitial.cc

@@ -21,6 +21,7 @@
 #include "base/values.h"
 #include "build/build_config.h"
 #include "components/prefs/pref_service.h"
+#include "components/supervised_user/core/browser/supervised_user_error_page.h"
 #include "components/supervised_user/core/browser/supervised_user_service.h"
 #include "components/supervised_user/core/browser/supervised_user_utils.h"
 #include "components/supervised_user/core/browser/web_content_handler.h"
@@ -75,16 +76,15 @@ std::string SupervisedUserInterstitial::GetHTMLContents(
     FilteringBehaviorReason reason,
     bool already_sent_request,
     bool is_main_frame,
-    const std::string& application_locale) {
-
+    const std::string& application_locale,
+    std::optional<float> ios_font_size_multiplier) {
   bool allow_access_requests =
       supervised_user_service->remote_web_approvals_manager()
           .AreApprovalRequestsEnabled();
-
   return BuildErrorPageHtml(
       allow_access_requests, supervised_user_service->GetCustodian(),
       supervised_user_service->GetSecondCustodian(), reason, application_locale,
-      already_sent_request, is_main_frame);
+      already_sent_request, is_main_frame, ios_font_size_multiplier);
 }
 
 void SupervisedUserInterstitial::GoBack() {

components/supervised_user/core/browser/supervised_user_interstitial.h

@@ -10,7 +10,7 @@
 
 #include "base/functional/callback_forward.h"
 #include "base/memory/raw_ref.h"
-#include "components/supervised_user/core/browser/supervised_user_error_page.h"
+#include "components/supervised_user/core/browser/supervised_user_utils.h"
 #include "url/gurl.h"
 
 class PrefService;
@@ -75,13 +75,15 @@ class SupervisedUserInterstitial {
       const std::u16string& supervised_user_name,
       FilteringBehaviorReason reason);
 
+  // Returns the HTML contents of the error page.
   static std::string GetHTMLContents(
       SupervisedUserService* supervised_user_service,
       PrefService* pref_service,
       FilteringBehaviorReason reason,
       bool already_sent_request,
       bool is_main_frame,
-      const std::string& application_locale);
+      const std::string& application_locale,
+      std::optional<float> font_size_multiplier = std::nullopt);
 
   void GoBack();
   void RequestUrlAccessRemote(base::OnceCallback<void(bool)> callback);

ios/chrome/browser/web/model/BUILD.gn

@@ -326,6 +326,7 @@ source_set("web_internal") {
     "//ios/components/security_interstitials/https_only_mode:feature",
     "//ios/components/security_interstitials/lookalikes",
     "//ios/components/security_interstitials/safe_browsing",
+    "//ios/components/ui_util",
     "//ios/components/webui:url_constants",
     "//ios/net",
     "//ios/public/provider/chrome/browser/additional_features:additional_features_api",

ios/chrome/browser/web/model/chrome_web_client.mm

@@ -94,6 +94,7 @@
 #import "ios/components/security_interstitials/lookalikes/lookalike_url_error.h"
 #import "ios/components/security_interstitials/safe_browsing/safe_browsing_error.h"
 #import "ios/components/security_interstitials/safe_browsing/safe_browsing_unsafe_resource_container.h"
+#import "ios/components/ui_util/dynamic_type_util.h"
 #import "ios/components/webui/web_ui_url_constants.h"
 #import "ios/net/protocol_handler_util.h"
 #import "ios/public/provider/chrome/browser/url_rewriters/url_rewriters_api.h"
@@ -213,7 +214,8 @@ NSString* GetSupervisedUserErrorPageHTML(web::WebState* web_state,
           profile->GetPrefs(), error_info->filtering_behavior_reason(),
           container->IsRemoteApprovalPendingForUrl(url),
           error_info->is_main_frame(),
-          GetApplicationContext()->GetApplicationLocale());
+          GetApplicationContext()->GetApplicationLocale(),
+          ui_util::SystemSuggestedFontSizeMultiplier());
 
   security_interstitials::IOSBlockingPageTabHelper::FromWebState(web_state)
       ->AssociateBlockingPage(navigation_id, std::move(page));

ios/components/security_interstitials/ios_security_interstitial_page.mm

@@ -7,10 +7,9 @@
 #import "base/check.h"
 #import "base/feature_list.h"
 #import "base/metrics/histogram_macros.h"
-#import "base/strings/string_number_conversions.h"
-#import "base/strings/stringprintf.h"
 #import "components/grit/components_resources.h"
 #import "components/security_interstitials/core/common_string_util.h"
+#import "components/security_interstitials/core/utils.h"
 #import "ios/components/security_interstitials/ios_blocking_page_controller_client.h"
 #import "ios/components/ui_util/dynamic_type_util.h"
 #import "ios/web/common/features.h"
@@ -20,24 +19,6 @@
 
 namespace security_interstitials {
 
-namespace {
-// Adjusts the interstitial page's template parameter "fontsize" by system font
-// size multiplier.
-void AdjustFontSize(base::Value::Dict& load_time_data) {
-  std::string* value = load_time_data.FindString("fontsize");
-  DCHECK(value);
-  std::string old_size = *value;
-  // `old_size` should be in form of "75%".
-  DCHECK(old_size.size() > 1 && old_size.back() == '%');
-  double new_size = 75.0;
-  bool converted =
-      base::StringToDouble(old_size.substr(0, old_size.size() - 1), &new_size);
-  DCHECK(converted);
-  new_size *= ui_util::SystemSuggestedFontSizeMultiplier();
-  load_time_data.Set("fontsize", base::StringPrintf("%.0lf%%", new_size));
-}
-}  // namespace
-
 IOSSecurityInterstitialPage::IOSSecurityInterstitialPage(
     web::WebState* web_state,
     const GURL& request_url,
@@ -55,7 +36,7 @@ std::string IOSSecurityInterstitialPage::GetHtmlContents() const {
   PopulateInterstitialStrings(load_time_data);
   webui::SetLoadTimeDataDefaults(client_->GetApplicationLocale(),
                                  &load_time_data);
-  AdjustFontSize(load_time_data);
+  AdjustFontSize(load_time_data, ui_util::SystemSuggestedFontSizeMultiplier());
   std::string html =
       ui::ResourceBundle::GetSharedInstance().LoadDataResourceString(
           IDR_SECURITY_INTERSTITIAL_HTML);