GN: Initialize Tool::defined_from_ in the constructor
set_defined_from() isn't called in some tests (e.g. those using TestWithScope),
thus calling defined_from() will only yield garbage, likely leading to a crash.
BUG=
Review-Url: https://codereview.chromium.org/2394323002
Cr-Original-Commit-Position: refs/heads/master@{#423698}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: fb7800730f213aba891c83df31b7183fc4cbcdc5
diff --git a/tools/gn/tool.cc b/tools/gn/tool.cc
index 139c032..2c955b8 100644
--- a/tools/gn/tool.cc
+++ b/tools/gn/tool.cc
@@ -5,7 +5,8 @@
#include "tools/gn/tool.h"
Tool::Tool()
- : depsformat_(DEPS_GCC),
+ : defined_from_(nullptr),
+ depsformat_(DEPS_GCC),
precompiled_header_type_(PCH_NONE),
restat_(false),
complete_(false) {
