Create the base Custom Context Menu Dialog.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index b8e710afffaab2371dde075e4b0bf7eb1c9b8649..a18337990deb64b4984b7570f3e383b67ab6b921 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -15032,6 +15032,15 @@ read aloud to screenreader users to announce that a completion is available.">
     <message name="IDS_FLAGS_MOJO_LOADING_DESCRIPTION" desc="Description for the flag to enable Mojo IPC for resource loading" translateable="false">
       Use Mojo IPC instead of traditional Chrome IPC for resource loading.
     </message>
+
+    <if expr="is_android">
+      <message name="IDS_FLAGS_ENABLE_CUSTOM_CONTEXT_MENU_NAME" desc="Name for the flag to enable the custom context menu" translateable="false">
+        Enable custom context menu
+      </message>
+      <message name="IDS_FLAGS_ENABLE_CUSTOM_CONTEXT_MENU_DESCRIPTION" desc="Description for the flag that enables the custom context menu">
+        Enables a new context menu when a link, image, or video is pressed within main Chrome.
+      </message>
+    </if>
   </messages>
  </release>
 </grit>