Disabling flaky SingleSampleMetricsFactoryImplTest.MultithreadedMetrics test

Example:
https://ci.chromium.org/p/chromium/builders/try/linux_chromium_asan_rel_ng/384996

TBR=asvitkine@chromium.org

Bug: 1009360
Change-Id: I24c0999ff863c3e6f4561cf3bb594eb75bc35e8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829347Reviewed-by: Sergey Poromov <poromov@chromium.org>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701076}

components/metrics/single_sample_metrics_factory_impl_unittest.cc

@@ -140,7 +140,8 @@ TEST_F(SingleSampleMetricsFactoryImplTest, DefaultSingleSampleMetricWithValue) {
                 base::HistogramBase::kUmaTargetedHistogramFlag));
 }
 
-TEST_F(SingleSampleMetricsFactoryImplTest, MultithreadedMetrics) {
+// TODO(crbug.com/1009360). Flaky timeouts.
+TEST_F(SingleSampleMetricsFactoryImplTest, DISABLED_MultithreadedMetrics) {
   base::HistogramTester tester;
   std::unique_ptr<base::SingleSampleMetric> metric =
       factory_->CreateCustomCountsMetric(kMetricName, kMin, kMax, kBucketCount);