Add an about:flag to enable client-side LoFi

This allows users to turn client-side LoFi on android.

BUG=720920

Review-Url: https://codereview.chromium.org/2870263004
Cr-Commit-Position: refs/heads/master@{#471030}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 7520fcd4..652dacf4 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1360,6 +1360,12 @@
 // Describes an about:flags experiment to enable offline page previews.
 extern const char kEnableOfflinePreviewsDescription[];
 
+// An about:flags experiment title to enable client-side Lo-Fi previews.
+extern const char kEnableClientLoFiName[];
+
+// Describes an about:flags experiment to enable client-side Lo-Fi previews.
+extern const char kEnableClientLoFiDescription[];
+
 #endif  // defined(OS_ANDROID)
 
 // Name of about:flags option for LCD text.