[cr147] blink::String::StartsWith renamed to starts_with.

Chromium change:
https://source.chromium.org/chromium/chromium/src/+/10c312329d52398ec70d591997ad0e5e0e82ff8c

commit 10c312329d52398ec70d591997ad0e5e0e82ff8c
Author: Kent Tamura <tkent@chromium.org>
Date:   Thu Feb 26 01:38:23 2026 -0800

    WTF: Rename String::StartsWith() to starts_with()

    The new name is consistent with std::string::starts_with().
    This CL has no behavior changes.

    Bug: 473854537

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

@@ -1103,7 +1103,7 @@ void PageGraph::GenerateReportForNode(const blink::DOMNodeId node_id,
 
   for (const GraphNode* succ : successors) {
     ItemName item_name = succ->GetItemName();
-    if (item_name.StartsWith("resource #")) {
+    if (item_name.starts_with("resource #")) {
       for (const GraphEdge* edge : succ->GetInEdges()) {
         String reportItem(edge->GetItemDesc() +
                           "\r\n\r\nby: " + edge->GetOutNode()->GetItemDesc());