Add an experimental flag for offlining.

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 b173d2b49123df227dfd23847aa9f6ca89573176..5145f81cd1103f3c68f2b43bab59981c44407cdd 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -14961,6 +14961,12 @@ Please check your email at <ph name="ACCOUNT_EMAIL">$2<ex>jane.doe@gmail.com</ex
       <message name="IDS_FLAGS_OFFLINING_RECENT_PAGES_DESCRIPTION" desc="Description for the flag to enable offlining of recently visited pages.">
         Enable storing recently visited pages locally for offline use. Requires Offline Pages to be enabled.
       </message>
+      <message name="IDS_FLAGS_OFFLINING_EXPERIMENTAL_NAME" desc="Name for the flag to enable experimental offlining features.">
+        Enable experimental offlining features
+      </message>
+      <message name="IDS_FLAGS_OFFLINING_EXPERIMENTAL_DESCRIPTION" desc="Description for the flag to enable experimental offlining features.">
+        Enable experimental offlining features. Requires Offline Pages to be enabled.
+      </message>
     </if>
 
     <if expr="not is_android and not is_ios and _google_chrome">