Add submodules.
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..d7dcfbf
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,6 @@
+[submodule "build"]
+	path = build
+	url = https://chromium.googlesource.com/chromium/tools/build
+[submodule "infra"]
+	path = infra
+	url = https://chromium.googlesource.com/infra/infra
diff --git a/build b/build
new file mode 160000
index 0000000..86a77b2
--- /dev/null
+++ b/build
@@ -0,0 +1 @@
+Subproject commit 86a77b2cb61e12ba01f79956b984b7e5939d2aac
diff --git a/infra b/infra
new file mode 160000
index 0000000..697d9a3
--- /dev/null
+++ b/infra
@@ -0,0 +1 @@
+Subproject commit 697d9a3547cedc87abbf61edf70e7d4dae12fbbc