Add Clang static analyzer to Clang toolchain defs in GN

build/toolchain/clang_static_analyzer.gni

Index: build/toolchain/clang_static_analyzer.gni
diff --git a/build/toolchain/clang_static_analyzer.gni b/build/toolchain/clang_static_analyzer.gni
new file mode 100644
index 0000000000000000000000000000000000000000..b689c1b7c230e67fc51609602eb7aff7da54bdbb
--- /dev/null
+++ b/build/toolchain/clang_static_analyzer.gni
@@ -0,0 +1,10 @@
+# Copyright (c) 2017 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.
+
+# Defines the configuration of Clang static analysis tools.
+
+declare_args() {
+  # Uses the Clang static analysis tools during compilation.
+  use_clang_static_analyzer = false
+}