telemetry: increase the default timeout value

The system_health.memory_desktop test takes about 2h5m to finish --
slightly exceeds the timeout value defined in telemetry_runner.py. In
order to make this test work, the timeout value has to be increased.

BUG=chromium:753279
TEST=`test_that --board reef --args="local=True" "${DUT_IP}"
      telemetry_Benchmarks.system_health.memory_desktop`
    and saw it finished in 2h5m

Change-Id: Iba13e66e6774159c56c17bcc64cae7258bc7ab81
Reviewed-on: https://chromium-review.googlesource.com/690054
Commit-Ready: Mao Huang <littlecvr@chromium.org>
Tested-by: Mao Huang <littlecvr@chromium.org>
Reviewed-by: Chung-yih Wang <cywang@google.com>
diff --git a/server/cros/telemetry_runner.py b/server/cros/telemetry_runner.py
index c78bb94..fd424b8 100644
--- a/server/cros/telemetry_runner.py
+++ b/server/cros/telemetry_runner.py
@@ -13,7 +13,7 @@
 TELEMETRY_RUN_BENCHMARKS_SCRIPT = 'tools/perf/run_benchmark'
 TELEMETRY_RUN_TESTS_SCRIPT = 'tools/telemetry/run_tests'
 TELEMETRY_RUN_GPU_TESTS_SCRIPT = 'content/test/gpu/run_gpu_integration_test.py'
-TELEMETRY_TIMEOUT_MINS = 120
+TELEMETRY_TIMEOUT_MINS = 150
 
 DUT_CHROME_ROOT = '/usr/local/telemetry/src'
 DUT_COMMON_SSH_OPTIONS = ['-o StrictHostKeyChecking=no',