Use persistent memory for receiving metrics from sub-processes.

chrome/browser/metrics/subprocess_metrics_provider_unittest.cc

Index: chrome/browser/metrics/subprocess_metrics_provider_unittest.cc
diff --git a/chrome/browser/metrics/subprocess_metrics_provider_unittest.cc b/chrome/browser/metrics/subprocess_metrics_provider_unittest.cc
index 4f3779c68a80670173cb0fc8db0797384da56258..5b3e641d9eae898dd621b24099ac8a9dbfb78a4f 100644
--- a/chrome/browser/metrics/subprocess_metrics_provider_unittest.cc
+++ b/chrome/browser/metrics/subprocess_metrics_provider_unittest.cc
@@ -13,6 +13,7 @@
 #include "base/metrics/persistent_histogram_allocator.h"
 #include "base/metrics/persistent_memory_allocator.h"
 #include "base/metrics/statistics_recorder.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
@@ -56,7 +57,8 @@ class HistogramFlattenerDeltaRecorder : public base::HistogramFlattener {
 
 class SubprocessMetricsProviderTest : public testing::Test {
  protected:
-  SubprocessMetricsProviderTest() {
+  SubprocessMetricsProviderTest()
+      : thread_bundle_(content::TestBrowserThreadBundle::DEFAULT) {
     // Get this first so it isn't created inside a persistent allocator.
     base::PersistentHistogramAllocator::GetCreateHistogramResultHistogram();
 
@@ -117,6 +119,11 @@ class SubprocessMetricsProviderTest : public testing::Test {
   }
 
  private:
+  // A thread-bundle makes the tests appear on the UI thread, something that is
+  // checked in methods called from the SubprocessMetricsProvider class under
+  // test. This must be constructed before the |provider_| field.
+  content::TestBrowserThreadBundle thread_bundle_;
+
   SubprocessMetricsProvider provider_;
   std::unique_ptr<base::StatisticsRecorder> test_recorder_;