Add flag for zip archiver on files app.

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 3e5e15d6d9fd7cd659e1feb2f354b90148e12538..101c2d8a070eb9a690582f49586df1d4668fe386 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2583,6 +2583,15 @@ const FeatureEntry kFeatureEntries[] = {
      FEATURE_VALUE_TYPE(chrome::android::kCustomContextMenu)},
 #endif  // OS_ANDROID
 
+#if defined(OS_CHROMEOS)
+    {"enable-zip-archiver-on-file-manager",
+     flag_descriptions::kEnableZipArchiverOnFileManagerName,
+     flag_descriptions::kEnableZipArchiverOnFileManagerDescription,
+     kOsCrOS,
+     SINGLE_VALUE_TYPE(
+         chromeos::switches::kEnableZipArchiverOnFileManager)},
+#endif  // OS_CHROMEOS
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in
     // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.