Add script to view URL in HTMLViewer

This script takes advantage of the fact that Mojo binaries are published in the
cloud to add functionality for viewing a URL in HTMLViewer embedded in the
kiosk window manager.

Review URL: https://codereview.chromium.org/982523004

Cr-Commit-Position: refs/heads/master@{#319085}

mojo/services/html_viewer/view_url.py

+#!/usr/bin/env python
+# Copyright 2015 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.
+
+import argparse
+import os
+import subprocess
+import sys
+
+root_path = os.path.realpath(
+    os.path.join(
+        os.path.dirname(
+            os.path.realpath(__file__)),
+        os.pardir,
+        os.pardir,
+        os.pardir))
+
+def _BuildShellCommand(args):
+  sdk_version = subprocess.check_output(["cat",
+      "third_party/mojo/src/mojo/public/VERSION"], cwd=root_path)
+  build_dir = os.path.join(root_path, args.build_dir)
+
+  shell_command = [os.path.join(build_dir, "mojo_shell")]
+
+  options = []
+  options.append(
+      "--origin=https://storage.googleapis.com/mojo/services/linux-x64/%s" %
+           sdk_version)
+  options.append("--url-mappings=mojo:html_viewer=file://%s/html_viewer.mojo" %
+                 build_dir)
+  options.append('--args-for=mojo:kiosk_wm %s' % args.url)
+
+  app_to_run = "mojo:kiosk_wm"
+
+  return shell_command + options + [app_to_run]
+
+def main():
+  parser = argparse.ArgumentParser(
+      description="View a URL with HTMLViewer in the Kiosk window manager. "
+                  "You must have built //mojo/services/html_viewer and "
+                  "//mojo/services/network first. Note that this will "
+                  "currently often fail spectacularly due to lack of binary "
+                  "stability in Mojo.")
+  parser.add_argument(
+      "--build-dir",
+      help="Path to the dir containing the linux-x64 binaries relative to the "
+           "repo root (default: %(default)s)",
+      default="out/Release")
+  parser.add_argument("url",
+                      help="The URL to be viewed")
+
+  args = parser.parse_args()
+  return subprocess.call(_BuildShellCommand(args))
+
+if __name__ == '__main__':
+  sys.exit(main())