Moving scripts to download and build apprtc/collider.

We are starting to move code to setup our tests from [1].
We are moving only scripts to download and build apprtc, collider and node
(scripts that work on firefox have not been copied by this CL).

[1] - https://chromium.googlesource.com/chromium/deps/webrtc/webrtc.DEPS/

BUG=webrtc:7602
NOTRY=True

Review-Url: https://codereview.webrtc.org/2861653005
Cr-Commit-Position: refs/heads/master@{#18060}

webrtc/tools/testing/setup_apprtc.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python
+# Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+"""This script sets up AppRTC and its dependencies.
+
+Requires that depot_tools is installed and in the PATH.
+
+It will put the result under <output_dir>/collider.
+"""
+
+import os
+import sys
+
+import utils
+
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+
+def main(argv):
+  if len(argv) == 1:
+    return 'Usage %s <output_dir>' % argv[0]
+
+  output_dir = argv[1]
+  apprtc_appengine_mercurial_path = os.path.join(
+      SCRIPT_DIR, 'download_apprtc_appengine_and_mercurial.py')
+  utils.RunSubprocessWithRetry([apprtc_appengine_mercurial_path,
+                                output_dir])
+
+  download_golang_path = os.path.join(SCRIPT_DIR, 'download_golang.py')
+  utils.RunSubprocessWithRetry([download_golang_path, output_dir])
+
+  build_mercurial_path = os.path.join(SCRIPT_DIR, 'build_mercurial_local.py')
+  hg_dir = os.path.join(output_dir, 'mercurial')
+  utils.RunSubprocessWithRetry([build_mercurial_path, hg_dir])
+
+  build_apprtc_collider_path = os.path.join(SCRIPT_DIR,
+                                            'build_apprtc_collider.py')
+  apprtc_src_dir = os.path.join(output_dir, 'apprtc', 'src')
+  go_dir = os.path.join(output_dir, 'go')
+  collider_dir = os.path.join(output_dir, 'collider')
+  utils.RunSubprocessWithRetry([build_apprtc_collider_path, apprtc_src_dir,
+                                go_dir, hg_dir, collider_dir])
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))