app_list: Create an app_list_switches.* to put all app list switches.

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index ca6a75372069ebae3b662133812ac2cc844e0f20..24c3e2e896a1fb2ef4a48a688dfacc4d787a1688 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -7,10 +7,6 @@
 namespace ash {
 namespace switches {
 
-// Show only apps result in app list search.
-// TODO(xiyuan): Create an app_list_switches.cc to put all app list switches.
-const char kAppListShowAppsOnly[] = "app-list-show-apps-only";
-
 // Enable keyboard shortcuts useful for debugging.
 const char kAshDebugShortcuts[] = "ash-debug-shortcuts";