Add extensions code to use common updater in components/update_client/

extensions/shell/common/switches.cc

Index: extensions/shell/common/switches.cc
diff --git a/extensions/shell/common/switches.cc b/extensions/shell/common/switches.cc
index fbb578379ef8ec927ebba022e0bc0734df154c1e..66bd7e58390190eaba7188d9e7c70d79e231b0c2 100644
--- a/extensions/shell/common/switches.cc
+++ b/extensions/shell/common/switches.cc
@@ -13,9 +13,6 @@ const char kAppShellAllowRoaming[] = "app-shell-allow-roaming";
 // Size for the host window to create (i.e. "800x600").
 const char kAppShellHostWindowSize[] = "app-shell-host-window-size";
 
-// ID of an extension CRX to be downloaded from the web store.
-const char kAppShellInstallCrx[] = "app-shell-install-crx";
-
 // SSID of the preferred WiFi network.
 const char kAppShellPreferredNetwork[] = "app-shell-preferred-network";