diff --git a/metrics/timer_test.cc b/metrics/timer_test.cc
new file mode 100644
index 0000000..445aeeb
--- /dev/null
+++ b/metrics/timer_test.cc
@@ -0,0 +1,162 @@
+// Copyright (c) 2011 The Chromium OS 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/memory/scoped_ptr.h>
+#include <base/time.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "metrics_library_mock.h"
+#include "timer.h"
+#include "timer_mock.h"
+
+using ::testing::_;
+using ::testing::Return;
+
+namespace chromeos_metrics {
+
+class TimerTest : public testing::Test {
+ public:
+  TimerTest() : clock_wrapper_mock_(new ClockWrapperMock()) {}
+
+ protected:
+  virtual void SetUp() {
+    EXPECT_FALSE(timer_.is_started_);
+    stime += base::TimeDelta::FromMilliseconds(1500);
+    etime += base::TimeDelta::FromMilliseconds(3000);
+  }
+
+  virtual void TearDown() {}
+
+  Timer timer_;
+  scoped_ptr<ClockWrapperMock> clock_wrapper_mock_;
+  base::TimeTicks stime, etime;
+};
+
+TEST_F(TimerTest, StartStop) {
+  EXPECT_CALL(*clock_wrapper_mock_, GetCurrentTime())
+      .WillOnce(Return(stime))
+      .WillOnce(Return(etime));
+  timer_.clock_wrapper_.reset(clock_wrapper_mock_.release());
+  ASSERT_TRUE(timer_.Start());
+  ASSERT_TRUE(timer_.start_time_ == stime);
+  ASSERT_TRUE(timer_.HasStarted());
+  ASSERT_TRUE(timer_.Stop());
+  ASSERT_EQ(timer_.elapsed_time_.InMilliseconds(), 1500);
+  ASSERT_FALSE(timer_.HasStarted());
+}
+
+TEST_F(TimerTest, ReStart) {
+  EXPECT_CALL(*clock_wrapper_mock_, GetCurrentTime())
+      .WillOnce(Return(stime))
+      .WillOnce(Return(etime));
+  timer_.clock_wrapper_.reset(clock_wrapper_mock_.release());
+  timer_.Start();
+  base::TimeTicks buffer = timer_.start_time_;
+  timer_.Start();
+  ASSERT_FALSE(timer_.start_time_ == buffer);
+}
+
+TEST_F(TimerTest, Reset) {
+  EXPECT_CALL(*clock_wrapper_mock_, GetCurrentTime())
+      .WillOnce(Return(stime));
+  timer_.clock_wrapper_.reset(clock_wrapper_mock_.release());
+  timer_.Start();
+  ASSERT_TRUE(timer_.Reset());
+  ASSERT_FALSE(timer_.HasStarted());
+}
+
+TEST_F(TimerTest, SeparatedTimers) {
+  base::TimeTicks stime2, etime2;
+  stime2 += base::TimeDelta::FromMilliseconds(4200);
+  etime2 += base::TimeDelta::FromMilliseconds(5000);
+  EXPECT_CALL(*clock_wrapper_mock_, GetCurrentTime())
+      .WillOnce(Return(stime))
+      .WillOnce(Return(etime))
+      .WillOnce(Return(stime2))
+      .WillOnce(Return(etime2));
+  timer_.clock_wrapper_.reset(clock_wrapper_mock_.release());
+  ASSERT_TRUE(timer_.Start());
+  ASSERT_TRUE(timer_.Stop());
+  ASSERT_EQ(timer_.elapsed_time_.InMilliseconds(), 1500);
+  ASSERT_TRUE(timer_.Start());
+  ASSERT_TRUE(timer_.start_time_ == stime2);
+  ASSERT_TRUE(timer_.Stop());
+  ASSERT_EQ(timer_.elapsed_time_.InMilliseconds(), 800);
+  ASSERT_FALSE(timer_.HasStarted());
+}
+
+TEST_F(TimerTest, InvalidStop) {
+  EXPECT_CALL(*clock_wrapper_mock_, GetCurrentTime())
+      .WillOnce(Return(stime))
+      .WillOnce(Return(etime));
+  timer_.clock_wrapper_.reset(clock_wrapper_mock_.release());
+  ASSERT_FALSE(timer_.Stop());
+  // Now we try it again, but after a valid start/stop.
+  timer_.Start();
+  timer_.Stop();
+  base::TimeDelta elapsed_time = timer_.elapsed_time_;
+  ASSERT_FALSE(timer_.Stop());
+  ASSERT_TRUE(elapsed_time == timer_.elapsed_time_);
+}
+
+TEST_F(TimerTest, InvalidElapsedTime) {
+  base::TimeDelta elapsed_time;
+  ASSERT_FALSE(timer_.GetElapsedTime(&elapsed_time));
+}
+
+static const char kMetricName[] = "test-timer";
+static const int kMinSample = 0;
+static const int kMaxSample = 120 * 1E6;
+static const int kNumBuckets = 50;
+
+class TimerReporterTest : public testing::Test {
+ public:
+  TimerReporterTest() : timer_reporter_(kMetricName, kMinSample, kMaxSample,
+                                        kNumBuckets),
+                        clock_wrapper_mock_(new ClockWrapperMock()) {}
+
+ protected:
+  virtual void SetUp() {
+    timer_reporter_.set_metrics_lib(&lib_);
+    EXPECT_EQ(timer_reporter_.histogram_name_, kMetricName);
+    EXPECT_EQ(timer_reporter_.min_, kMinSample);
+    EXPECT_EQ(timer_reporter_.max_, kMaxSample);
+    EXPECT_EQ(timer_reporter_.num_buckets_, kNumBuckets);
+    stime += base::TimeDelta::FromMilliseconds(1500);
+    etime += base::TimeDelta::FromMilliseconds(3000);
+  }
+
+  virtual void TearDown() {
+    timer_reporter_.set_metrics_lib(NULL);
+  }
+
+  TimerReporter timer_reporter_;
+  MetricsLibraryMock lib_;
+  scoped_ptr<ClockWrapperMock> clock_wrapper_mock_;
+  base::TimeTicks stime, etime;
+};
+
+TEST_F(TimerReporterTest, StartStopReport) {
+  EXPECT_CALL(*clock_wrapper_mock_, GetCurrentTime())
+      .WillOnce(Return(stime))
+      .WillOnce(Return(etime));
+  timer_reporter_.clock_wrapper_.reset(clock_wrapper_mock_.release());
+  EXPECT_CALL(lib_, SendToUMA(kMetricName, 1500, kMinSample, kMaxSample,
+                              kNumBuckets)).WillOnce(Return(true));
+  ASSERT_TRUE(timer_reporter_.Start());
+  ASSERT_TRUE(timer_reporter_.Stop());
+  ASSERT_TRUE(timer_reporter_.ReportMilliseconds());
+}
+
+TEST_F(TimerReporterTest, InvalidReport) {
+  ASSERT_FALSE(timer_reporter_.ReportMilliseconds());
+}
+
+}  // namespace chromeos_metrics
+
+int main(int argc, char **argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}