Kokoro: Add configurations for GN presubmit

Issue: #2421

kokoro/linux-clang-gn/build-docker.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+# Copyright (C) 2020 Google, Inc.
+#
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+#    Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+#
+#    Redistributions in binary form must reproduce the above
+#    copyright notice, this list of conditions and the following
+#    disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#
+#    Neither the name of Google Inc. nor the names of its
+#    contributors may be used to endorse or promote products derived
+#    from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+set -e # Fail on any error.
+set -x # Display commands being run.
+
+echo "Fetching depot_tools..."
+mkdir -p /tmp/depot_tools
+curl https://storage.googleapis.com/chrome-infra/depot_tools.zip -o /tmp/depot_tools.zip
+unzip /tmp/depot_tools.zip -d /tmp/depot_tools
+rm /tmp/depot_tools.zip
+export PATH="/tmp/depot_tools:$PATH"
+
+echo "Syncing client..."
+gclient sync --gclientfile=standalone.gclient
+gn gen out/Default
+
+echo "Building..."
+cd out/Default
+ninja