Add high-precision timing histograms.

components/subresource_filter/core/common/scoped_timers_unittest.cc

Index: components/subresource_filter/core/common/scoped_timers_unittest.cc
diff --git a/components/subresource_filter/core/common/scoped_timers_unittest.cc b/components/subresource_filter/core/common/scoped_timers_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..80cc66c11ac101d5c3dda71ad4c1599c2058cba6
--- /dev/null
+++ b/components/subresource_filter/core/common/scoped_timers_unittest.cc
@@ -0,0 +1,121 @@
+// 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 "components/subresource_filter/core/common/scoped_timers.h"
+
+#include "base/test/histogram_tester.h"
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class ExportFunctorForTests {
+ public:
+  int number_of_calls() const { return number_of_calls_; }
+  void operator()(base::TimeDelta) { ++number_of_calls_; }
+
+ private:
+  int number_of_calls_ = 0;
+};
+
+// Casts an l-value parameter to a reference to it.
+template <typename T>
+T& reference(T& value) {
+  return value;
+}
+
+}  // namespace
+
+namespace subresource_filter {
+
+TEST(ScopedTimersTest, ScopedTimerCallsFunctor) {
+  ExportFunctorForTests export_functor;
+  {
+    // Reference is needed to bypass object copying.
+    SCOPED_TIMER(reference(export_functor));
+    EXPECT_EQ(0, export_functor.number_of_calls());
+  }
+  EXPECT_EQ(1, export_functor.number_of_calls());
+}
+
+TEST(ScopedTimersTest, ScopedThreadTimerCallsFunctor) {
+  ExportFunctorForTests export_functor;
+  {
+    // Reference is needed to bypass functor copying.
+    SCOPED_THREAD_TIMER(reference(export_functor));
+    EXPECT_EQ(0, export_functor.number_of_calls());
+  }
+  const int expected_number_of_calls = base::ThreadTicks::IsSupported() ? 1 : 0;
+  EXPECT_EQ(expected_number_of_calls, export_functor.number_of_calls());
+}
+
+TEST(ScopedTimersTest, ScopedTimersCopyFunctor) {
+  ExportFunctorForTests export_functor;
+  {
+    SCOPED_TIMER(export_functor);
+    SCOPED_THREAD_TIMER(export_functor);
+    EXPECT_EQ(0, export_functor.number_of_calls());
+  }
+  EXPECT_EQ(0, export_functor.number_of_calls());
+}
+
+TEST(ScopedTimersTest, ScopedThreadTimerCallsStoredLambdaFunctor) {
+  bool export_is_called = false;
+  auto export_functor = [&export_is_called](base::TimeDelta) {
+    EXPECT_FALSE(export_is_called);
+    export_is_called = true;
+  };
+
+  {
+    SCOPED_THREAD_TIMER(export_functor);
+    EXPECT_FALSE(export_is_called);
+  }
+  EXPECT_EQ(base::ThreadTicks::IsSupported(), export_is_called);
+}
+
+TEST(ScopedTimersTest, ScopedTimerCallsStoredLambdaFunctor) {
+  bool export_is_called = false;
+  auto export_functor = [&export_is_called](base::TimeDelta) {
+    export_is_called = true;
+  };
+
+  {
+    SCOPED_TIMER(export_functor);
+    EXPECT_FALSE(export_is_called);
+  }
+  EXPECT_TRUE(export_is_called);
+}
+
+TEST(ScopedTimersTest, ScopedUmaHistogramMacros) {
+  base::HistogramTester tester;
+  {
+    SCOPED_UMA_HISTOGRAM_THREAD_TIMER("ScopedTimers.ThreadTimer");
+    SCOPED_UMA_HISTOGRAM_MICRO_THREAD_TIMER("ScopedTimers.MicroThreadTimer");
+    SCOPED_UMA_HISTOGRAM_MICRO_TIMER("ScopedTimers.MicroTimer");
+
+    tester.ExpectTotalCount("ScopedTimers.ThreadTimer", 0);
+    tester.ExpectTotalCount("ScopedTimers.MicroThreadTimer", 0);
+    tester.ExpectTotalCount("ScopedTimers.MicroTimer", 0);
+  }
+
+  const int expected_count = base::ThreadTicks::IsSupported() ? 1 : 0;
+  tester.ExpectTotalCount("ScopedTimers.ThreadTimer", expected_count);
+  tester.ExpectTotalCount("ScopedTimers.MicroThreadTimer", expected_count);
+
+  tester.ExpectTotalCount("ScopedTimers.MicroTimer", 1);
+}
+
+TEST(ScopedTimersTest, UmaHistogramMicroTimesFromExportFunctor) {
+  base::HistogramTester tester;
+  auto export_functor = [](base::TimeDelta delta) {
+    UMA_HISTOGRAM_MICRO_TIMES("ScopedTimers.MicroTimes", delta);
+  };
+  {
+    SCOPED_TIMER(export_functor);
+    tester.ExpectTotalCount("ScopedTimers.MicroTimes", 0);
+  }
+  tester.ExpectTotalCount("ScopedTimers.MicroTimes", 1);
+}
+
+}  // namespace subresource_filter