[cr149] String::Substring renamed to DeprecatedSubstring

Chromium changes:
https://chromium.googlesource.com/chromium/src/+/c6f8d3ab428ec002d18b29ecd18c0c124b667e87

commit c6f8d3ab428ec002d18b29ecd18c0c124b667e87
Author: Kent Tamura <tkent@chromium.org>
Date:   Thu Apr 9 01:44:49 2026 -0700

    WTF: Rename String::Substring() to DeprecatedSubstring()

    * inspector_css_parser_observer.cc:
      A DCHECK assumes `comment_text` is not empty, so `start_offset`
      should not be greater than `parsed_text_.length()`. We can use
      subview().

    Bug: 473854537
    Change-Id: Ia38b03fd58755e9370037c483bce7bfd5482343e
    Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7740859
    Auto-Submit: Kent Tamura <tkent@chromium.org>
    Reviewed-by: Fredrik Söderquist <fs@opera.com>
    Commit-Queue: Fredrik Söderquist <fs@opera.com>
    Cr-Commit-Position: refs/heads/main@{#1612041}

third_party/blink/renderer/core/brave_page_graph/page_graph.cc

@@ -853,7 +853,7 @@ void PageGraph::RegisterPageGraphWebAPICallWithResult(
       blink::Vector<String> cookie_structure = value.SplitSkippingEmpty('=');
       String cookie_key = *(cookie_structure.begin());
       String cookie_value =
-          value.Substring(cookie_key.length() + 1, value.length());
+          value.DeprecatedSubstring(cookie_key.length() + 1, value.length());
       RegisterStorageWrite(execution_context, cookie_key,
                            base::Value(cookie_value.Utf8()),
                            brave_page_graph::StorageLocation::kCookie);
@@ -936,7 +936,7 @@ void PageGraph::RegisterPageGraphJavaScriptUrl(blink::Document* document,
           .script_code =
               blink::DecodeUrlEscapeSequences(
                   url.GetString(), blink::DecodeUrlMode::kUtf8OrIsomorphic)
-                  .Substring(kJavascriptSchemeLength),
+                  .DeprecatedSubstring(kJavascriptSchemeLength),
           .parent_script_id = GetExecutingScriptId(execution_context),
       });
 }

third_party/blink/renderer/core/farbling/brave_session_cache.cc

@@ -405,7 +405,7 @@ bool BraveSessionCache::AllowFontFamily(
     case BraveFarblingLevel::MAXIMUM: {
       if (AllowFontByFamilyName(
               family_name,
-              blink::DefaultLanguage().GetString().Substring(0, 2))) {
+              blink::DefaultLanguage().GetString().DeprecatedSubstring(0, 2))) {
         return true;
       }
       if (IsFontAllowedForFarbling(family_name)) {