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

chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc

Index: chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
diff --git a/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc b/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
index 539c6d2ab1f927e28e9ae85b52c046fac83e8769..aeeeabd4e60fbc9c79bc4beafb57645a6badefed 100644
--- a/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
+++ b/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
@@ -118,6 +118,7 @@
 #include "chrome/browser/chromeos/printer_detector/printer_detector_factory.h"
 #include "chrome/browser/chromeos/printing/cups_print_job_manager_factory.h"
 #include "chrome/browser/chromeos/printing/printers_manager_factory.h"
+#include "chrome/browser/chromeos/tether/tether_service_factory.h"
 #include "chrome/browser/extensions/api/platform_keys/verify_trust_api.h"
 #endif
 
@@ -234,6 +235,7 @@ EnsureBrowserContextKeyedServiceFactoriesBuilt() {
   chromeos::PrinterDetectorFactory::GetInstance();
   chromeos::CupsPrintJobManagerFactory::GetInstance();
   chromeos::PrintersManagerFactory::GetInstance();
+  TetherServiceFactory::GetInstance();
   extensions::VerifyTrustAPI::GetFactoryInstance();
 #endif
   FaviconServiceFactory::GetInstance();