Make signin_scoped_device_id enabled by default.

chrome/browser/signin/chrome_signin_client.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/signin/chrome_signin_client.h"
 
 #include "base/command_line.h"
 #include "base/guid.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 115 matching lines @@
   if (profile_->IsSupervised()) {
     LOG(ERROR) << "Attempt to revoke supervised user refresh "
                << "token detected, ignoring.";
     return false;
   }
 #endif
   return true;
 }
 
 std::string ChromeSigninClient::GetSigninScopedDeviceId() {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableSigninScopedDeviceId)) {
+    return std::string();
+  }
+
   std::string signin_scoped_device_id =
       GetPrefs()->GetString(prefs::kGoogleServicesSigninScopedDeviceId);
-  if (CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableSigninScopedDeviceId) &&
-      signin_scoped_device_id.empty()) {
+  if (signin_scoped_device_id.empty()) {
     // If device_id doesn't exist then generate new and save in prefs.
     signin_scoped_device_id = base::GenerateGUID();
     DCHECK(!signin_scoped_device_id.empty());
     GetPrefs()->SetString(prefs::kGoogleServicesSigninScopedDeviceId,
                           signin_scoped_device_id);
   }
   return signin_scoped_device_id;
 }
 
 void ChromeSigninClient::ClearSigninScopedDeviceId() {
@@ skipping 67 matching lines @@
 
 void ChromeSigninClient::UnregisterForCookieChangedNotification() {
   // Note that it's allowed to call this method multiple times without an
   // intervening call to |RegisterForCookieChangedNotification()|.
   content::Source<Profile> source(profile_);
   if (!registrar_.IsRegistered(
       this, chrome::NOTIFICATION_COOKIE_CHANGED, source))
     return;
   registrar_.Remove(this, chrome::NOTIFICATION_COOKIE_CHANGED, source);
 }