[Doodle] Add an about:flags entry for the new Doodle API

chrome/browser/android/chrome_feature_list.cc

Index: chrome/browser/android/chrome_feature_list.cc
diff --git a/chrome/browser/android/chrome_feature_list.cc b/chrome/browser/android/chrome_feature_list.cc
index e313b4f7c19ed235131ac5cc2067477102dc4182..4d6b2a306063cb479959f7e0a9ef8bbc33568ff1 100644
--- a/chrome/browser/android/chrome_feature_list.cc
+++ b/chrome/browser/android/chrome_feature_list.cc
@@ -180,6 +180,9 @@ const base::Feature kTabReparenting{"TabReparenting",
 const base::Feature kUploadCrashReportsUsingJobScheduler{
     "UploadCrashReportsUsingJobScheduler", base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kUseNewDoodleApi{"UseNewDoodleApi",
+                                     base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kUserMediaScreenCapturing{
     "UserMediaScreenCapturing", base::FEATURE_DISABLED_BY_DEFAULT};