Add about flag for offline page experiment

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 5bc0eddf6e40ea359900bffc945f7c3feddde1dc..967ab839b4d5cfab8f6df73ef8eb1c1af12d00ca 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -31,6 +31,7 @@
 #include "components/enhanced_bookmarks/enhanced_bookmark_switches.h"
 #include "components/metrics/metrics_hashes.h"
 #include "components/nacl/common/nacl_switches.h"
+#include "components/offline_pages/offline_page_switches.h"
 #include "components/omnibox/browser/omnibox_switches.h"
 #include "components/plugins/common/plugins_switches.h"
 #include "components/proximity_auth/switches.h"
@@ -2099,6 +2100,14 @@ const Experiment kExperiments[] = {
      kOsAndroid,
      MULTI_VALUE_TYPE(kProgressBarAnimationChoices)},
 #endif  // defined(OS_ANDROID)
+#if defined(OS_ANDROID)
+    {"offline-pages",

[fgorski, 2015/08/04 23:28:07]

Did you consider:
enable-offline-pages
or
offline-pages-experiment ?

Also, did you figure out how the default is established?

[jianli, 2015/08/04 23:39:03]

This is the internal name that is not exposed to the user. The names of switches
seen by the user are kEnableOfflinePages and kDisableOfflinePages. I think
"offline-pages" is better since it is indeed meant for 3 states. Also adding
"-experiment" seems to be unnecessary.
By default, we will be using the value from field trial signal.

+     IDS_FLAGS_OFFLINE_PAGES_NAME,
+     IDS_FLAGS_OFFLINE_PAGES_DESCRIPTION,
+     kOsAndroid,
+     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableOfflinePages,
+                               switches::kDisableOfflinePages)},
+#endif  // defined(OS_ANDROID)
 
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in