MB: Make it possible to specify timeout.

webrtc_perf_tests needs more than 15 min to run.

NOTRY=True

Bug: chromium:755660
Change-Id: Ibabfae3679206105d585c35f80b839f0046f9ccc
Reviewed-on: https://webrtc-review.googlesource.com/4021
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Commit-Queue: Edward Lemur <ehmaldonado@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19996}
diff --git a/tools_webrtc/mb/mb.py b/tools_webrtc/mb/mb.py
index 8e57d39..2cd54f2 100755
--- a/tools_webrtc/mb/mb.py
+++ b/tools_webrtc/mb/mb.py
@@ -1098,6 +1098,7 @@
         ]
         sep = '\\' if self.platform == 'win32' else '/'
         output_dir = '${ISOLATED_OUTDIR}' + sep + 'test_logs'
+        timeout = isolate_map[target].get('timeout', 900)
         gtest_parallel_wrapper = [
             '../../tools_webrtc/gtest-parallel-wrapper.py',
             '--output_dir=%s' % output_dir,
@@ -1105,7 +1106,7 @@
             # We tell gtest-parallel to interrupt the test after 900 seconds,
             # so it can exit cleanly and report results, instead of being
             # interrupted by swarming and not reporting anything.
-            '--timeout=900',
+            '--timeout=%s' % timeout,
             '--retry_failed=3',
         ]