Revert of Revert of Clean up Smart Lock cryptohome keys logic:

chrome/browser/signin/easy_unlock_service_regular.cc

Index: chrome/browser/signin/easy_unlock_service_regular.cc
diff --git a/chrome/browser/signin/easy_unlock_service_regular.cc b/chrome/browser/signin/easy_unlock_service_regular.cc
index d1d7c03a22f4f3d7d798b7638ecb1126b06e12bc..c4b72c7236baf41990f9eb8bee61cbff7fa98c79 100644
--- a/chrome/browser/signin/easy_unlock_service_regular.cc
+++ b/chrome/browser/signin/easy_unlock_service_regular.cc
@@ -91,19 +91,29 @@
       base::ThreadTaskRunnerHandle::Get().get()));
 
   OpenSetupApp();
-}
-
-void EasyUnlockServiceRegular::OnKeysRefreshedForSetDevices(bool success) {
-  // If the keys were refreshed successfully, the hardlock state should be
-  // cleared, so Smart Lock can be used normally. Otherwise, we fall back to
-  // a hardlock state to force the user to type in their credentials again.
-  if (success) {
-    SetHardlockStateForUser(GetUserEmail(),
-                            EasyUnlockScreenlockStateHandler::NO_HARDLOCK);
-  }
-
-  // Even if the keys refresh suceeded, we still fetch the cryptohome keys as a
-  // sanity check.
+
+  // Use this opportunity to clear the crytohome keys if it was not already
+  // cleared earlier.
+  const base::ListValue* devices = GetRemoteDevices();
+  if (!devices || devices->empty()) {
+    chromeos::EasyUnlockKeyManager* key_manager =
+        chromeos::UserSessionManager::GetInstance()->GetEasyUnlockKeyManager();
+    key_manager->RefreshKeys(
+        user_context, base::ListValue(),
+        base::Bind(&EasyUnlockServiceRegular::SetHardlockAfterKeyOperation,
+                   weak_ptr_factory_.GetWeakPtr(),
+                   EasyUnlockScreenlockStateHandler::NO_PAIRING));
+  }
+}
+
+void EasyUnlockServiceRegular::SetHardlockAfterKeyOperation(
+    EasyUnlockScreenlockStateHandler::HardlockState state_on_success,
+    bool success) {
+  if (success)
+    SetHardlockStateForUser(GetUserEmail(), state_on_success);
+
+  // Even if the refresh keys operation suceeded, we still fetch and check the
+  // cryptohome keys against the keys in local preferences as a sanity check.
   CheckCryptohomeKeysAndMaybeHardlock();
 }
 #endif
@@ -157,34 +167,30 @@
     const base::ListValue& devices) {
   DictionaryPrefUpdate pairing_update(profile()->GetPrefs(),
                                       prefs::kEasyUnlockPairing);
-  pairing_update->SetWithoutPathExpansion(kKeyDevices, devices.DeepCopy());
+  if (devices.empty())
+    pairing_update->RemoveWithoutPathExpansion(kKeyDevices, NULL);
+  else
+    pairing_update->SetWithoutPathExpansion(kKeyDevices, devices.DeepCopy());
 
 #if defined(OS_CHROMEOS)
   // TODO(tengs): Investigate if we can determine if the remote devices were set
   // from sync or from the setup app.
-  if (short_lived_user_context_ && short_lived_user_context_->user_context() &&
-      !devices.empty()) {
+  if (short_lived_user_context_ && short_lived_user_context_->user_context()) {
     // We may already have the password cached, so proceed to create the
     // cryptohome keys for sign-in or the system will be hardlocked.
-    chromeos::UserSessionManager::GetInstance()->GetEasyUnlockKeyManager()
+    chromeos::UserSessionManager::GetInstance()
+        ->GetEasyUnlockKeyManager()
         ->RefreshKeys(
-            *short_lived_user_context_->user_context(),
-            devices,
-            base::Bind(&EasyUnlockServiceRegular::OnKeysRefreshedForSetDevices,
-                       weak_ptr_factory_.GetWeakPtr()));
+            *short_lived_user_context_->user_context(), devices,
+            base::Bind(&EasyUnlockServiceRegular::SetHardlockAfterKeyOperation,
+                       weak_ptr_factory_.GetWeakPtr(),
+                       EasyUnlockScreenlockStateHandler::NO_HARDLOCK));
   } else {
     CheckCryptohomeKeysAndMaybeHardlock();
   }
 #else
   CheckCryptohomeKeysAndMaybeHardlock();
 #endif
-}
-
-void EasyUnlockServiceRegular::ClearRemoteDevices() {
-  DictionaryPrefUpdate pairing_update(profile()->GetPrefs(),
-                                      prefs::kEasyUnlockPairing);
-  pairing_update->RemoveWithoutPathExpansion(kKeyDevices, NULL);
-  CheckCryptohomeKeysAndMaybeHardlock();
 }
 
 void EasyUnlockServiceRegular::RunTurnOffFlow() {
@@ -302,7 +308,7 @@
     return;
   }
 
-  ClearRemoteDevices();
+  SetRemoteDevices(base::ListValue());
   SetTurnOffFlowStatus(IDLE);
   ReloadApp();
 }