Revert of Clean up Smart Lock cryptohome keys logic:

chrome/browser/extensions/api/easy_unlock_private/easy_unlock_private_api.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/extensions/api/easy_unlock_private/easy_unlock_private_api.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
@@ skipping 549 matching lines @@
 EasyUnlockPrivateSetRemoteDevicesFunction::
     ~EasyUnlockPrivateSetRemoteDevicesFunction() {
 }
 
 bool EasyUnlockPrivateSetRemoteDevicesFunction::RunSync() {
   scoped_ptr<easy_unlock_private::SetRemoteDevices::Params> params(
       easy_unlock_private::SetRemoteDevices::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
   Profile* profile = Profile::FromBrowserContext(browser_context());
-  base::ListValue devices;
-  for (size_t i = 0; i < params->devices.size(); ++i) {
-    devices.Append(params->devices[i]->ToValue().release());
+  if (params->devices.empty()) {
+    EasyUnlockService::Get(profile)->ClearRemoteDevices();
+  } else {
+    base::ListValue devices;
+    for (size_t i = 0; i < params->devices.size(); ++i) {
+      devices.Append(params->devices[i]->ToValue().release());
+    }
+    EasyUnlockService::Get(profile)->SetRemoteDevices(devices);
   }
-  EasyUnlockService::Get(profile)->SetRemoteDevices(devices);
 
   return true;
 }
 
 EasyUnlockPrivateGetRemoteDevicesFunction::
     EasyUnlockPrivateGetRemoteDevicesFunction() {
 }
 
 EasyUnlockPrivateGetRemoteDevicesFunction::
     ~EasyUnlockPrivateGetRemoteDevicesFunction() {
@@ skipping 121 matching lines @@
   // TODO(tengs): Find a way to get the profile picture for non-ChromeOS
   // devices.
   results_ = easy_unlock_private::GetUserImage::Results::Create("");
   SetError("Not supported on non-ChromeOS platforms.");
 #endif
   return true;
 }
 
 }  // namespace api
 }  // namespace extensions