Create the base Custom Context Menu Dialog.

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 de9802166bb5b36c1ed76387f35ca248baa440f2..2d9479f50513541433d67ada8f9f903699cfc844 100644
--- a/chrome/browser/android/chrome_feature_list.cc
+++ b/chrome/browser/android/chrome_feature_list.cc
@@ -51,6 +51,7 @@ const base::Feature* kFeaturesExposedToJava[] = {
     &kChromeHomeFeature,
     &kContextualSearchSingleActions,
     &kContextualSearchUrlActions,
+    &kCustomContextMenu,
     &kCustomFeedbackUi,
     &kImportantSitesInCBD,
     &kImprovedA2HS,
@@ -121,6 +122,9 @@ const base::Feature kContextualSearchSingleActions{
 const base::Feature kContextualSearchUrlActions{
     "ContextualSearchUrlActions", base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kCustomContextMenu{"CustomContextMenu",
+                                       base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kCustomFeedbackUi{"CustomFeedbackUi",
                                       base::FEATURE_DISABLED_BY_DEFAULT};