Add ffmpeg and zxing to webrtc/tools/video_quality_toolchain.

tools/video_quality_toolchain/download.py

Index: tools/video_quality_toolchain/download.py
diff --git a/tools/video_quality_toolchain/download.py b/tools/video_quality_toolchain/download.py
new file mode 100755
index 0000000000000000000000000000000000000000..24c243af15c698686f1fa5e3cd4d3820d35aa3d5
--- /dev/null
+++ b/tools/video_quality_toolchain/download.py
@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+# Copyright (c) 2016 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.
+
+"""Downloads precompiled tools needed for video quality analysis."""
+
+import os
+import subprocess
+import sys
+
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+
+
+def main():
+  cmd = [
+    'download_from_google_storage',
+    '--directory',
+    '--num_threads=10',
+    '--bucket', 'chrome-webrtc-resources',
+    '--auto_platform',
+    '--recursive',
+    SCRIPT_DIR,
+  ]
+  print 'Downloading video quality analysis tools...'
+  subprocess.check_call(cmd)
+
+
+if __name__ == '__main__':
+  sys.exit(main())