Create and pass shared-histogram-allocator from browser to renderer.

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 "base/memory/shared_memory.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 "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+const uint32_t TEST_MEMORY_SIZE = 64 << 10;  // 64 KiB
+}  // namespace
+
+class HistogramFlattenerDeltaRecorder : public base::HistogramFlattener {
+ public:
+  HistogramFlattenerDeltaRecorder() {}
+
+  void RecordDelta(const base::HistogramBase& histogram,
+                   const base::HistogramSamples& snapshot) override {
+    recorded_delta_histogram_names_.push_back(histogram.histogram_name());
+  }
+
+  void InconsistencyDetected(
+      base::HistogramBase::Inconsistency problem) override {
+    ASSERT_TRUE(false);
+  }
+
+  void UniqueInconsistencyDetected(
+      base::HistogramBase::Inconsistency problem) override {
+    ASSERT_TRUE(false);
+  }
+
+  void InconsistencyDetectedInLoggedCount(int amount) override {
+    ASSERT_TRUE(false);
+  }
+
+  std::vector<std::string> GetRecordedDeltaHistogramNames() {
+    return recorded_delta_histogram_names_;
+  }
+
+ private:
+  std::vector<std::string> recorded_delta_histogram_names_;
+
+  DISALLOW_COPY_AND_ASSIGN(HistogramFlattenerDeltaRecorder);
+};
+
+class SubprocessMetricsProviderTest : public testing::Test {
+ protected:
+  SubprocessMetricsProviderTest() {
+    // Get this first so it isn't created inside a persistent allocator.
+    base::PersistentHistogramAllocator::GetCreateHistogramResultHistogram();
+  }
+
+  void TearDown() override {
+    base::PersistentHistogramAllocator::ReleaseGlobalAllocatorForTesting();
+  }
+
+  SubprocessMetricsProvider* provider() {
+    if (!provider_)
+      provider_.reset(new SubprocessMetricsProvider());
+    return provider_.get();
+  }
+
+ private:
+  scoped_ptr<SubprocessMetricsProvider> provider_;
+
+  DISALLOW_COPY_AND_ASSIGN(SubprocessMetricsProviderTest);
+};
+
+TEST_F(SubprocessMetricsProviderTest, SnapshotMetrics) {
+  scoped_ptr<base::SharedMemory> shmem1(new base::SharedMemory());
+  base::SharedMemoryHandle memory_handle;
+  ASSERT_TRUE(shmem1->CreateAndMapAnonymous(TEST_MEMORY_SIZE));
+  ASSERT_TRUE(shmem1->ShareToProcess(base::GetCurrentProcessHandle(),
+                                     &memory_handle));
+
+  base::PersistentHistogramAllocator::CreateGlobalAllocatorOnSharedMemory(
+      std::move(shmem1), TEST_MEMORY_SIZE, 0, "");
+  base::HistogramBase* foo = base::Histogram::FactoryGet("foo", 1, 100, 10, 0);
+  base::HistogramBase* bar = base::Histogram::FactoryGet("bar", 1, 100, 10, 0);
+  foo->Add(42);
+  bar->Add(84);
+
+  scoped_ptr<base::SharedMemory> shmem2(
+      new base::SharedMemory(memory_handle, /*readonly=*/false));
+  ASSERT_TRUE(shmem2->Map(TEST_MEMORY_SIZE));
+
+  scoped_ptr<base::SharedPersistentMemoryAllocator> allocator(
+      new base::SharedPersistentMemoryAllocator(
+          std::move(shmem2), 0, "", false));
+  provider()->RegisterSubprocessAllocator(123, make_scoped_ptr(
+      new base::PersistentHistogramAllocator(std::move(allocator))));
+
+  // Recording should find the two histograms created in persistent memory.
+  {
+    HistogramFlattenerDeltaRecorder flattener;
+    base::HistogramSnapshotManager snapshot_manager(&flattener);
+    snapshot_manager.StartDeltas();
+    provider()->RecordHistogramSnapshots(&snapshot_manager);
+    snapshot_manager.FinishDeltas();
+    EXPECT_EQ(2U, flattener.GetRecordedDeltaHistogramNames().size());
+  }
+
+  // A second run should have nothing to producte except one internal metric.
+  {
+    HistogramFlattenerDeltaRecorder flattener;
+    base::HistogramSnapshotManager snapshot_manager(&flattener);
+    snapshot_manager.StartDeltas();
+    provider()->RecordHistogramSnapshots(&snapshot_manager);
+    snapshot_manager.FinishDeltas();
+    EXPECT_EQ(1U, flattener.GetRecordedDeltaHistogramNames().size());
+  }
+
+  // Create a new histogram and update existing ones. Should now report 4 items.
+  base::HistogramBase* baz = base::Histogram::FactoryGet("baz", 1, 100, 10, 0);
+  baz->Add(1969);
+  foo->Add(10);
+  bar->Add(20);
+  {
+    HistogramFlattenerDeltaRecorder flattener;
+    base::HistogramSnapshotManager snapshot_manager(&flattener);
+    snapshot_manager.StartDeltas();
+    provider()->RecordHistogramSnapshots(&snapshot_manager);
+    snapshot_manager.FinishDeltas();
+    EXPECT_EQ(4U, flattener.GetRecordedDeltaHistogramNames().size());
+  }
+}