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..34785a7a19ddb82ea87a9658750ed9e269ad7fa3 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_OFFLINE_PAGES_CT_NAME" desc="Name for the flag to enable offlining CT features.">
+        Enable Offline Pages CT features.
+      </message>
+      <message name="IDS_FLAGS_OFFLINE_PAGES_CT_DESCRIPTION" desc="Description for the flag to enable offline pages CT features.">
+        Enable Offline Pages CT features. Requires Offline Pages to be enabled.

[jianli, 2016/06/16 21:53:38]

nit: remove "Requires Offline Pages to be enabled."

+      </message>
     </if>
 
     <if expr="not is_android and not is_ios and _google_chrome">