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/about_flags.cc b/chrome/browser/about_flags.cc
index 1baf8743..ae9f5333 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1897,6 +1897,9 @@
     {"enable-offline-previews", flag_descriptions::kEnableOfflinePreviewsName,
      flag_descriptions::kEnableOfflinePreviewsDescription, kOsAndroid,
      FEATURE_VALUE_TYPE(previews::features::kOfflinePreviews)},
+    {"enable-client-lo-fi", flag_descriptions::kEnableClientLoFiName,
+     flag_descriptions::kEnableClientLoFiDescription, kOsAndroid,
+     FEATURE_VALUE_TYPE(previews::features::kClientLoFi)},
 #endif  // OS_ANDROID
     {"allow-insecure-localhost", flag_descriptions::kAllowInsecureLocalhost,
      flag_descriptions::kAllowInsecureLocalhostDescription, kOsAll,
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index ee29df2..35a4e984 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1213,6 +1213,11 @@
 const char kEnableOfflinePreviewsDescription[] =
     "Enable showing offline page previews on slow networks.";
 
+const char kEnableClientLoFiName[] = "Client-side Lo-Fi previews";
+
+const char kEnableClientLoFiDescription[] =
+    "Enable showing low fidelity images on some pages on slow networks.";
+
 #endif  // defined(OS_ANDROID)
 
 const char kLcdTextName[] = "LCD text antialiasing";
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.