Further increase run_benchmark timeout

Looks like the chromium page sets still hit the 10 min timeout.

BUG=skia:5700

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2342
# This code is not exercised by trybots.
NOTRY=true

Change-Id: I57aba4c1541a840d7e4e97112a6485abc20aa3c7
Reviewed-on: https://skia-review.googlesource.com/2342
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>

tools/skp/webpages_playback.py

@@ -290,7 +290,7 @@ class SkPicturePlayback(object):
       run_benchmark_cmd = (
           'PYTHONPATH=%s:%s:$PYTHONPATH' % (page_set_dir, self._catapult_dir),
           'DISPLAY=%s' % X11_DISPLAY,
-          'timeout', '600',
+          'timeout', '1800',
           os.path.join(self._telemetry_binaries_dir, 'run_benchmark'),
           '--extra-browser-args="%s"' % self._browser_args,
           '--browser=exact',