[Sync] Fix crash in GCP when adding encrypted entry that already exists.

sync/internal_api/write_node.cc

Index: sync/internal_api/write_node.cc
diff --git a/sync/internal_api/write_node.cc b/sync/internal_api/write_node.cc
index 0f57315122004a3a470ec2156c3c7c8a40938948..ff0a97f3094ea0b5aec8836c4d97f91aa44e91cf 100644
--- a/sync/internal_api/write_node.cc
+++ b/sync/internal_api/write_node.cc
@@ -374,6 +374,8 @@ WriteNode::InitUniqueByCreationResult WriteNode::InitUniqueByCreationImpl(
       existing_entry->PutParentId(parent_id);
     }  // Else just reuse the existing entry.
     entry_ = existing_entry.release();
+    if (!DecryptIfNecessary())
+      return INIT_FAILED_DECRYPT_EXISTING_ENTRY;
   } else {
     entry_ = new syncable::MutableEntry(transaction_->GetWrappedWriteTrans(),
                                         syncable::CREATE,