Use a stable device-user identifier for CryptAuth enrollments.

chrome/browser/signin/easy_unlock_service.cc

Index: chrome/browser/signin/easy_unlock_service.cc
diff --git a/chrome/browser/signin/easy_unlock_service.cc b/chrome/browser/signin/easy_unlock_service.cc
index 430a98f3671abd7370e5b052d907cbf417dbbb7a..a70603804decb19104df90895c716cd811bb2642 100644
--- a/chrome/browser/signin/easy_unlock_service.cc
+++ b/chrome/browser/signin/easy_unlock_service.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/guid.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/prefs/pref_registry_simple.h"
@@ -219,8 +220,9 @@ void EasyUnlockService::RegisterProfilePrefs(
 
 // static
 void EasyUnlockService::RegisterPrefs(PrefRegistrySimple* registry) {
-  registry->RegisterDictionaryPref(prefs::kEasyUnlockLocalStateUserPrefs);
+  registry->RegisterStringPref(prefs::kEasyUnlockDeviceId, std::string());
   registry->RegisterDictionaryPref(prefs::kEasyUnlockHardlockState);
+  registry->RegisterDictionaryPref(prefs::kEasyUnlockLocalStateUserPrefs);
 #if defined(OS_CHROMEOS)
   EasyUnlockTpmKeyManager::RegisterLocalStatePrefs(registry);
 #endif
@@ -269,6 +271,20 @@ EasyUnlockService::UserSettings EasyUnlockService::GetUserSettings(
   return user_settings;
 }
 
+// static
+std::string EasyUnlockService::GetDeviceId() {
+  PrefService* local_state = GetLocalState();
+  if (!local_state)
+    return std::string();
+
+  std::string device_id = local_state->GetString(prefs::kEasyUnlockDeviceId);
+  if (device_id.empty()) {
+    device_id = base::GenerateGUID();
+    local_state->SetString(prefs::kEasyUnlockDeviceId, device_id);
+  }
+  return device_id;
+}
+
 void EasyUnlockService::Initialize(
     scoped_ptr<EasyUnlockAppManager> app_manager) {
   app_manager_ = app_manager.Pass();