Add a flag to enable Translate Compact Infobar on Android.

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 0989d5f39a7030b0ddfe553eec3230516590ece1..71e30172f20df70029993975fe7dcd9701f75b59 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1347,6 +1347,11 @@ const char kPullToRefreshEffectName[] = "The pull-to-refresh effect";
 const char kPullToRefreshEffectDescription[] =
     "Page reloads triggered by vertically overscrolling content.";
 
+const char kTranslateCompactUIName[] = "New Translate Infobar";
+
+const char kTranslateCompactUIDescription[] =
+    "Enable the new Translate compact infobar UI.";
+
 #endif  // defined(OS_ANDROID)
 
 #if defined(OS_MACOSX)