Expose UkmService to content/

content/public/browser/content_browser_client.cc

Index: content/public/browser/content_browser_client.cc
diff --git a/content/public/browser/content_browser_client.cc b/content/public/browser/content_browser_client.cc
index 7f00fb51046525198fe4a6d4458f08e508718458..5c2ab72ff53768100801c3a2b5026bd466f8480e 100644
--- a/content/public/browser/content_browser_client.cc
+++ b/content/public/browser/content_browser_client.cc
@@ -450,6 +450,10 @@ ContentBrowserClient::GetMemoryCoordinatorDelegate() {
   return nullptr;
 }
 
+::ukm::UkmRecorder* ContentBrowserClient::GetUkmRecorder() {
+  return nullptr;
+}
+
 std::unique_ptr<base::TaskScheduler::InitParams>
 ContentBrowserClient::GetTaskSchedulerInitParams() {
   return nullptr;