Log operator code histogram on new metric log

chrome/browser/metrics/metrics_service_unittest.cc

Index: chrome/browser/metrics/metrics_service_unittest.cc
diff --git a/chrome/browser/metrics/metrics_service_unittest.cc b/chrome/browser/metrics/metrics_service_unittest.cc
index b42d789e29cf3cdf5092ba29b71b8f43257e68ce..398a05fe4ef64cf47144dddecb04022bc7fd38c7 100644
--- a/chrome/browser/metrics/metrics_service_unittest.cc
+++ b/chrome/browser/metrics/metrics_service_unittest.cc
@@ -135,6 +135,22 @@ class MetricsServiceTest : public testing::Test {
   DISALLOW_COPY_AND_ASSIGN(MetricsServiceTest);
 };
 
+class TestMetricsServiceObserver : public MetricsServiceObserver {
+ public:
+  TestMetricsServiceObserver(): observed_(0) {}
+  virtual ~TestMetricsServiceObserver() {}
+
+  virtual void OnDidCreateMetricsLog() OVERRIDE {
+    ++observed_;
+  }
+  int observed() const { return observed_; }
+
+ private:
+  int observed_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestMetricsServiceObserver);
+};
+
 }  // namespace
 
 TEST_F(MetricsServiceTest, IsPluginProcess) {
@@ -304,3 +320,34 @@ TEST_F(MetricsServiceTest, CrashReportingEnabled) {
   EXPECT_FALSE(MetricsServiceHelper::IsCrashReportingEnabled());
 #endif  // defined(GOOGLE_CHROME_BUILD)
 }
+
+TEST_F(MetricsServiceTest, MetricsServiceObserver) {
+  MetricsService service;
+  TestMetricsServiceObserver observer1;
+  TestMetricsServiceObserver observer2;
+
+  service.AddObserver(&observer1);
+  EXPECT_EQ(0, observer1.observed());
+  EXPECT_EQ(0, observer2.observed());
+
+  service.OpenNewLog();
+  EXPECT_EQ(1, observer1.observed());
+  EXPECT_EQ(0, observer2.observed());
+  service.log_manager_.FinishCurrentLog();
+
+  service.AddObserver(&observer2);
+
+  service.OpenNewLog();
+  EXPECT_EQ(2, observer1.observed());
+  EXPECT_EQ(1, observer2.observed());
+  service.log_manager_.FinishCurrentLog();
+
+  service.RemoveObserver(&observer1);
+
+  service.OpenNewLog();
+  EXPECT_EQ(2, observer1.observed());
+  EXPECT_EQ(2, observer2.observed());
+  service.log_manager_.FinishCurrentLog();
+
+  service.RemoveObserver(&observer2);
+}