[Lit]: Add build time mangler for lit-html templates

.eslintrc.js

@@ -68,6 +68,7 @@ module.exports = {
     ],
     'object-shorthand': 0,
     'n/no-callback-literal': 0,
+    'no-template-curly-in-string': 0,
     '@typescript-eslint/await-thenable': 0,
     '@typescript-eslint/consistent-generic-constructors': 0,
     '@typescript-eslint/ban-ts-comment': 0,

PRESUBMIT.py

@@ -49,6 +49,36 @@ def _web_files_filter(affected_file):
     except RuntimeError as err:
         return [output_api.PresubmitError(err.args[1])]
 
+
+# Ensure Typescript files which we use as part of the build process are typechecked.
+def CheckTypescriptBuildFilesCompile(input_api, output_api):
+
+    def build_files_filter(affected_file):
+        return input_api.FilterSourceFile(affected_file,
+                                          files_to_check=[
+                                              r'.+\.mangle\.html\.ts$',
+                                              r'.+lit_mangler_cli\.ts$',
+                                              r'.+lit_mangler\.ts$',
+                                          ])
+
+    affected_files = input_api.AffectedFiles(file_filter=build_files_filter)
+    if not any(affected_files):
+        return []
+
+    files_to_check = [f.AbsoluteLocalPath() for f in affected_files]
+
+    try:
+        brave_node.RunNode([
+            brave_node.PathInNodeModules('tsx', 'dist', 'cli.mjs'),
+            '--tsconfig',
+            './tsconfig-mangle.json',
+            './tools/chromium_src/lit_mangler/lit_mangler_cli.ts',
+            'typecheck',
+        ] + files_to_check)
+    except RuntimeError as err:
+        return [output_api.PresubmitError(err.args[1])]
+    return []
+
 # Check and fix formatting issues (supports --fix).
 def CheckPatchFormatted(input_api, output_api):
     # Use git cl format to format supported files with Chromium formatters.
@@ -147,7 +177,11 @@ def CheckESLint(input_api, output_api):
         r'.+\.ts$',
         r'.+\.tsx$',
     )
-    files_to_skip = input_api.DEFAULT_FILES_TO_SKIP
+
+    # ESLint struggles with the dynamic import for the mangler here, and it
+    # isn't possible to disable that specific check.
+    files_to_skip = input_api.DEFAULT_FILES_TO_SKIP + (
+        r".+lit_mangler.*\.ts", )
 
     file_filter = lambda f: input_api.FilterSourceFile(
         f, files_to_check=files_to_check, files_to_skip=files_to_skip)

build/commands/lib/util.js

@@ -551,6 +551,13 @@ const util = {
     sourceFiles.forEach(chromiumSrcFile => {
       const relativeChromiumSrcFile = chromiumSrcFile.slice(chromiumSrcDirLen)
       let overriddenFile = path.join(config.srcDir, relativeChromiumSrcFile)
+
+      // .mangle.html.ts files are used to modify the upstream .html.ts file at
+      // build time.
+      if (overriddenFile.endsWith('.mangle.html.ts')) {
+        overriddenFile = overriddenFile.replace('.mangle.html.ts', '.html.ts')
+      }
+
       if (fs.existsSync(overriddenFile)) {
         // If overriddenFile is older than file in chromium_src, touch it to trigger rebuild.
         isDirty |= updateFileUTimesIfOverrideIsNewer(overriddenFile, chromiumSrcFile)

chromium_src/chrome/browser/resources/extensions/detail_view.mangle.html.ts

@@ -0,0 +1,16 @@
+// Copyright (c) 2025 The Brave Authors. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+import { mangle } from 'lit_mangler'
+
+mangle((element) => {
+    const section = element.querySelector('.section-content')
+    if (!section) {
+        throw new Error('[Brave Extensions Overrides] Could not find .section-content. Has the ID changed?')
+    }
+    section.textContent = '$i18n{privateInfoWarning}'
+    section.append('<span ?hidden=${!this.data.incognitoAccess.isActive}> $i18n{spanningInfoWarning}</span>')
+    section.append('<span> $i18n{privateAndTorInfoWarning}</span>')
+}, t => t.text.includes('id="allow-incognito"'))

chromium_src/tools/grit/preprocess_if_expr.py

@@ -9,7 +9,7 @@
 import shutil
 import json
 
-from brave_chromium_utils import get_chromium_src_override, get_webui_overriden_file_name, get_webui_overridden_but_referenced_files
+from brave_chromium_utils import get_chromium_src_override, get_webui_overriden_file_name, get_webui_overridden_but_referenced_files, get_src_dir
 
 
 def purge_overrides(out_folder, in_files):
@@ -44,17 +44,42 @@ def maybe_keep_upstream_version(override_in_folder, out_folder, override_file):
     return None
 
 
+def run_mangler(mangler_file, preprocess_file):
+    """Runs the mangler on the given file"""
+    import subprocess
+    import brave_node
+
+    tsx = brave_node.PathInNodeModules('tsx', 'dist', 'cli.mjs')
+    ts_config = os.path.join(get_src_dir(), 'brave', 'tsconfig-mangle.json')
+    lit_mangler = os.path.join(get_src_dir(), 'brave', 'tools', 'chromium_src',
+                               'lit_mangler', 'lit_mangler_cli.ts')
+
+    # Note: We read from and write to the preprocess file - this way any
+    # preprocessing that upstream does will be mangled.
+    brave_node.RunNode([
+        tsx, '--tsconfig', ts_config, lit_mangler, 'mangle', '--typecheck',
+        '-m', mangler_file, '-i', preprocess_file, '-o', preprocess_file
+    ])
+
+
 def get_chromium_src_files(in_folder, in_files):
     """Gets all the overrides we have in brave-core for this target"""
     override_files = []
     for file in in_files:
         in_file = get_chromium_src_override(os.path.join(in_folder, file))
         if os.path.exists(in_file):
             override_files.append(file)
+        elif os.path.exists(in_file.replace('.html.ts', '.mangle.html.ts')):
+            override_files.append(file.replace('.html.ts', '.mangle.html.ts'))
 
     return override_files
 
 
+def should_run_mangler(in_file):
+    """Determines if we should run the mangler on the given file"""
+    return in_file.endswith('.mangle.html.ts')
+
+
 # Used to indicate that there are no overrides, so we don't need to reprocess
 class NoOverridesException(Exception):
     pass
@@ -92,6 +117,13 @@ def parse_args(self, original_method, argv):
             manifest_data = json.load(open(manifest_path))
 
         for override_file in overrides:
+            if should_run_mangler(override_file):
+                upstream_file = override_file.replace('.mangle.html.ts',
+                                                      '.html.ts')
+                run_mangler(os.path.join(override_root_folder, override_file),
+                            os.path.join(out_folder, upstream_file))
+                continue
+
             overridden_name = maybe_keep_upstream_version(
                 override_root_folder, out_folder, override_file)
             if overridden_name and args.out_manifest: