Hook up base unit tests and allocator to GN build.

build/config/allocator.gni

Index: build/config/allocator.gni
diff --git a/build/config/allocator.gni b/build/config/allocator.gni
new file mode 100644
index 0000000000000000000000000000000000000000..ef10c3dc314d380991f4317cd9e3f0a759a4732c
--- /dev/null
+++ b/build/config/allocator.gni
@@ -0,0 +1,14 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+if (is_android || cpu_arch == "mipsel") {
+  _default_allocator = "none"
+} else {
+  _default_allocator = "tcmalloc"
+}
+
+declare_args() {
+  # Memory allocator to use. Set to "none" to use default allocator.
+  use_allocator = _default_allocator
+}