Use persistent memory for receiving metrics from sub-processes.

chrome/browser/metrics/subprocess_metrics_provider_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/metrics/subprocess_metrics_provider.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/histogram_flattener.h"
 #include "base/metrics/histogram_snapshot_manager.h"
 #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 {
 
 const uint32_t TEST_MEMORY_SIZE = 64 << 10;  // 64 KiB
 
 class HistogramFlattenerDeltaRecorder : public base::HistogramFlattener {
  public:
   HistogramFlattenerDeltaRecorder() {}
 
@@ skipping 23 matching lines @@
  private:
   std::vector<std::string> recorded_delta_histogram_names_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramFlattenerDeltaRecorder);
 };
 
 }  // namespace
 
 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();
 
     // MergeHistogramDeltas needs to be called beause it uses a histogram
     // macro which caches a pointer to a histogram. If not done before setting
     // a persistent global allocator, then it would point into memory that
     // will go away.
     provider_.MergeHistogramDeltas();
 
     // Create a dedicated StatisticsRecorder for this test.
@@ skipping 40 matching lines @@
       int id,
       std::unique_ptr<base::PersistentHistogramAllocator> allocator) {
     provider_.RegisterSubprocessAllocator(id, std::move(allocator));
   }
 
   void DeregisterSubprocessAllocator(int id) {
     provider_.DeregisterSubprocessAllocator(id);
   }
 
  private:
+  // A thread-buldle makes the tests appear on the UI thread, something that is

[Alexei Svitkine (slow), 2016/08/19 16:31:56]

Nit: buldle -> bundle

[bcwhite, 2016/08/19 17:19:46]

Done.

+  // 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_;
 
   DISALLOW_COPY_AND_ASSIGN(SubprocessMetricsProviderTest);
 };
 
 TEST_F(SubprocessMetricsProviderTest, 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);
@@ skipping 24 matching lines @@
   foo->Add(10);
   bar->Add(20);
   DeregisterSubprocessAllocator(123);
   EXPECT_EQ(2U, GetSnapshotHistogramCount());
 
   // Further snapshots should be empty even if things have changed.
   foo->Add(10);
   bar->Add(20);
   EXPECT_EQ(0U, GetSnapshotHistogramCount());
 }