[Autofill] Remove the "Disable native Autofill UI" flag.

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 706c1e7656266d3ee1f89ac7b329e82730916282..70e7d02889fc7f35d763c381a51de55908cc26b4 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -361,10 +361,6 @@ const char kDisableLocalOnlyInstantExtendedAPI[] =
 const char kDisableMinimizeOnSecondLauncherItemClick[] =
     "disable-minimize-on-second-launcher-item-click";
 
-// Disables the native Autofill UI, which is part of the browser process rather
-// than part of the renderer process.  http://crbug.com/51644
-const char kDisableNativeAutofillUi[]       = "disable-new-autofill-ui";
-
 // Disables the menu on the NTP for accessing sessions from other devices.
 const char kDisableNTPOtherSessionsMenu[]   = "disable-ntp-other-sessions-menu";