[Easy signin] Wire up userClick auth attempt to easy unlock app and back

chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc

Index: chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
diff --git a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
index 17bd8fe4e7a53cef845b4f3fc5ca9bb786071eca..243670c2a1651d95b3be3c6de8ddb9538943b6b9 100644
--- a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
+++ b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.cc
@@ -56,8 +56,7 @@ void EasyUnlockKeyManager::RefreshKeys(const UserContext& user_context,
       devices,
       base::Bind(&EasyUnlockKeyManager::OnKeysCreated,
                  weak_ptr_factory_.GetWeakPtr(),
-                 user_context,
-                 devices,
+                 devices.size(),
                  callback)));
   create_keys_op_->Start();
 }
@@ -185,8 +184,7 @@ int EasyUnlockKeyManager::GetNextOperationId() {
 }
 
 void EasyUnlockKeyManager::OnKeysCreated(
-    const UserContext& user_context,
-    const EasyUnlockDeviceKeyDataList& devices,
+    size_t remove_start_index,
     const RefreshKeysCallback& callback,
     bool create_success) {
   scoped_ptr<EasyUnlockCreateKeysOperation> op = create_keys_op_.Pass();
@@ -194,7 +192,7 @@ void EasyUnlockKeyManager::OnKeysCreated(
     callback.Run(create_success);
 
   // Remove extra existing keys.
-  RemoveKeys(user_context, devices.size(), RemoveKeysCallback());
+  RemoveKeys(op->user_context(), remove_start_index, RemoveKeysCallback());

[Tim Song, 2014/09/23 19:37:59]

There might be a race condition here if RemoveKeys() is called again before this
operation finishes, so the first operation will be canceled.

Perhaps it would be a good idea to enforce that this manager only performs one
operation at any time.

[xiyuan, 2014/09/23 19:56:58]

Currently, we have a poor man's DCHECK(!HasPendingOperations()) in line 70 to
protect the case. Since key operations should only happen after user presents
credentials (and after a user confirmation UI in the future), the chances of the
racing is low.

[tbarzic, 2014/09/23 19:58:34]

I had a similar concern when this first got in, but afaik this is called only
once per session, so there should be ok (and there is a DCHECK for this in
RemoveKeys/RefreshKeys).

 }
 
 void EasyUnlockKeyManager::OnKeysRemoved(const RemoveKeysCallback& callback,