Add a flag to app_shell that allows roaming on cellular networks

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 446b424debb1b3221a2e7f21960e5811a76236f3..fbb578379ef8ec927ebba022e0bc0734df154c1e 100644
--- a/extensions/shell/common/switches.cc
+++ b/extensions/shell/common/switches.cc
@@ -7,6 +7,9 @@
 namespace extensions {
 namespace switches {
 
+// Allow roaming in the cellular network.
+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";