Add flag for zip archiver on files app.

This CL just adds a flags for zip archiver, a new chrome extension for
files app.

BUG=706851

Review-Url: https://codereview.chromium.org/2799233002
Cr-Commit-Position: refs/heads/master@{#462761}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 6788471..ed27798 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -2478,6 +2478,12 @@
 // Description of the touch support for screen magnifier flag.
 extern const char kEnableTouchSupportForScreenMagnifierDescription[];
 
+// Name of zip archiver on files app flag.
+extern const char kEnableZipArchiverOnFileManagerName[];
+
+// Description of zip archiver on files app flag.
+extern const char kEnableZipArchiverOnFileManagerDescription[];
+
 #endif  // defined(OS_CHROMEOS)
 
 #if defined(OS_ANDROID)