Record task durations on Renderer Main & Compositor threads.

base/debug/task_annotator_unittest.cc

 // Copyright 2014 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 "base/debug/task_annotator.h"
+#include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/pending_task.h"
+#include "base/test/histogram_tester.h"
+#include "base/test/scoped_command_line.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 namespace debug {
 namespace {
 
 void TestTask(int* result) {
   *result = 123;
 }
 
 }  // namespace
 
 TEST(TaskAnnotatorTest, QueueAndRunTask) {
   int result = 0;
   PendingTask pending_task(FROM_HERE, BindOnce(&TestTask, &result));
 
   TaskAnnotator annotator;
   annotator.DidQueueTask("TaskAnnotatorTest::Queue", pending_task);
   EXPECT_EQ(0, result);
   annotator.RunTask("TaskAnnotatorTest::Queue", &pending_task);
   EXPECT_EQ(123, result);
 }
 
+TEST(TaskAnnotatorTest, TaskTimeHistogram) {
+  base::test::ScopedCommandLine scoped_command_line;
+  base::CommandLine* command_line = scoped_command_line.GetProcessCommandLine();
+  command_line->AppendSwitchASCII(switches::kProfilerTiming, "0");
+
+  // --profiler-timing=0
+  base::PlatformThread::SetName("Compositor");
+
+  HistogramTester histogram_tester;
+  TaskAnnotator annotator;
+
+  int result = 0;
+  PendingTask pending_task(FROM_HERE, BindOnce(&TestTask, &result));
+
+  annotator.DidQueueTask("TaskAnnotatorTest::Queue", pending_task);
+  annotator.RunTask("TaskAnnotatorTest::Queue", &pending_task);
+
+  histogram_tester.ExpectTotalCount("Scheduling.TaskTime.Compositor", 1);
+}
+
 }  // namespace debug
 }  // namespace base