assistant: config log file size

Bug: None
Test: locally build
Change-Id: I621187794e1261d4fc7c91221dfb5bfaa3eef079
Reviewed-on: https://chromium-review.googlesource.com/c/1266599Reviewed-by: Muyuan Li <muyuanli@chromium.org>
Commit-Queue: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597388}

chromeos/services/assistant/utils.cc

@@ -53,6 +53,9 @@ std::string CreateLibAssistantConfig(bool disable_hotword) {
     logging.SetKey(
         "directory",
         Value(GetRootPath().Append(FILE_PATH_LITERAL("log")).value()));
+    // Maximum disk space consumed by all log files. There are 5 rotating log
+    // files on disk.
+    logging.SetKey("max_size_kb", Value(3 * 1024));
     // Empty "output_type" disables logging to stderr.
     logging.SetKey("output_type", Value(Type::LIST));
     config.SetKey("logging", std::move(logging));