Control zero suggest with a pref, not a switch.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index a968fe5b2de1b77ec5d317dcfbbecec68c1c1a3f..d2041b8e37eaafd2573315450882aa6732997a17 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -674,11 +674,6 @@ const char kEnableWebSocketOverSpdy[]       = "enable-websocket-over-spdy";
 const char kExperimentalSpellcheckerFeatures[] =
     "experimental-spellchecker-features";
 
-// If nonempty, fetch experimental zero-suggest suggestions by appending to
-// this prefix of a URL.
-const char kExperimentalZeroSuggestURLPrefix[] =
-    "experimental-zero-suggest-url-prefix";
-
 // Explicitly allows additional ports using a comma-separated list of port
 // numbers.
 const char kExplicitlyAllowedPorts[]        = "explicitly-allowed-ports";