Disable flaky test SnapshotMetrics

SubprocessMetricsProviderTest.SnapshotMetrics has been flaky for a while
but it is suddenly much worse now and I don't see an obvious culprit.
Disabling until someone can investigate.

Tbr: asvitkine@chromium.org
Bug: 863262
Change-Id: I33d62b866c00f7fd9386cb274773547a3815bb20
Reviewed-on: https://chromium-review.googlesource.com/1136051
Commit-Queue: Kim Paulhamus <kpaulhamus@chromium.org>
Reviewed-by: Kim Paulhamus <kpaulhamus@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574944}

chrome/browser/metrics/subprocess_metrics_provider_unittest.cc

@@ -113,7 +113,8 @@ class SubprocessMetricsProviderTest : public testing::Test {
   DISALLOW_COPY_AND_ASSIGN(SubprocessMetricsProviderTest);
 };
 
-TEST_F(SubprocessMetricsProviderTest, SnapshotMetrics) {
+// Temporarily disabled until someone can troubleshoot http://crbug.com/863262
+TEST_F(SubprocessMetricsProviderTest, DISABLED_SnapshotMetrics) {
   base::HistogramBase* foo = base::Histogram::FactoryGet("foo", 1, 100, 10, 0);
   base::HistogramBase* bar = base::Histogram::FactoryGet("bar", 1, 100, 10, 0);
   base::HistogramBase* baz = base::Histogram::FactoryGet("baz", 1, 100, 10, 0);