Purge the App Launcher code from Windows.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 92fbcc38d05fee9e5e3d5175b9308d6224f7c1c5..d03ee8f30e7ead7ba333dd313980def0ee3e3362 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -2081,9 +2081,6 @@ const char kAppListEnableMethod[] = "app_list.how_enabled";
 // The time that the app launcher was enabled. Cleared when UMA is recorded.
 const char kAppListEnableTime[] = "app_list.when_enabled";
 
-// The last time the app list was launched.
-const char kAppListLastLaunchTime[] = "app_list.last_launch";
-
 #if defined(OS_MACOSX)
 // Integer representing the version of the app launcher shortcut installed on
 // the system. Incremented, e.g., when embedded icons change.