Add an option to 'git cl web' to print the issue URL instead of opening it.

This new option (-n,--no-browser) prints the issue URL instead of opening it in
the browser. This is helpful, for instance, if you're SSH'ed in from a
Chromebook.

Change-Id: I28793280901f054af4eed2dbf2ce1fd109b8d37b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4121245
Commit-Queue: Orr Bernstein <orrb@google.com>
Reviewed-by: Joanna Wang <jojwang@chromium.org>

git_cl.py

@@ -5025,7 +5025,13 @@ def CMDupstream(parser, args):
 @metrics.collector.collect_metrics('git cl web')
 def CMDweb(parser, args):
   """Opens the current CL in the web browser."""
-  _, args = parser.parse_args(args)
+  parser.add_option('-p',
+                    '--print-only',
+                    action='store_true',
+                    dest='print_only',
+                    help='Only print the Gerrit URL, don\'t open it in the '
+                    'browser.')
+  (options, args) = parser.parse_args(args)
   if args:
     parser.error('Unrecognized args: %s' % ' '.join(args))
 
@@ -5034,6 +5040,10 @@ def CMDweb(parser, args):
     print('ERROR No issue to open', file=sys.stderr)
     return 1
 
+  if options.print_only:
+    print(issue_url)
+    return 0
+
   # Redirect I/O before invoking browser to hide its output. For example, this
   # allows us to hide the "Created new window in existing browser session."
   # message from Chrome. Based on https://stackoverflow.com/a/2323563.