Create TetherService, a TetherAllowed pref, and use DependencyManager for RegisterProfilePrefs call…

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 f661e898abf90ddd10a592eb3c5761397e58372d..ee4935e8e3f31838db684267105b829d08944a24 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -966,6 +966,9 @@ const char kPinUnlockWeakPinsAllowed[] = "pin_unlock_weak_pins_allowed";
 // Boolean pref indicating whether fingerprint unlock is enabled.
 const char kEnableQuickUnlockFingerprint[] =
     "settings.enable_quick_unlock_fingerprint";
+
+// Whether a user is allowed to use Tether.
+const char kTetherAllowed[] = "tether.allowed";
 #endif  // defined(OS_CHROMEOS)
 
 // A boolean pref set to true if a Home button to open the Home pages should be