Add helper macros for calling a histogram with different names.

webrtc/system_wrappers/source/metrics_unittest.cc

Index: webrtc/system_wrappers/source/metrics_unittest.cc
diff --git a/webrtc/system_wrappers/source/metrics_unittest.cc b/webrtc/system_wrappers/source/metrics_unittest.cc
index 8319b78ee0d0daf35535a5327d8d320253f79b1a..05af478a294408266259134c49d1de2d172cb8b5 100644
--- a/webrtc/system_wrappers/source/metrics_unittest.cc
+++ b/webrtc/system_wrappers/source/metrics_unittest.cc
@@ -21,6 +21,9 @@ const std::string kName = "Name";
 void AddSparseSample(const std::string& name, int sample) {
   RTC_HISTOGRAM_COUNTS_SPARSE_100(name, sample);
 }
+void AddSampleWithVaryingName(int index, const std::string& name, int sample) {
+  RTC_HISTOGRAMS_COUNTS_100(index, name, sample);
+}
 #if GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
 void AddSample(const std::string& name, int sample) {
   RTC_HISTOGRAM_COUNTS_100(name, sample);
@@ -72,6 +75,19 @@ TEST(MetricsTest, RtcHistogramCounts_AddMultipleSamples) {
   EXPECT_EQ(kNumSamples - 1, test::LastHistogramSample(kName));
 }
 
+TEST(MetricsTest, RtcHistogramsCounts_AddSample) {
+  test::ClearHistograms();
+  AddSampleWithVaryingName(0, "Name1", kSample);
+  AddSampleWithVaryingName(1, "Name2", kSample + 1);
+  AddSampleWithVaryingName(2, "Name3", kSample + 2);
+  EXPECT_EQ(1, test::NumHistogramSamples("Name1"));
+  EXPECT_EQ(1, test::NumHistogramSamples("Name2"));
+  EXPECT_EQ(1, test::NumHistogramSamples("Name3"));
+  EXPECT_EQ(kSample + 0, test::LastHistogramSample("Name1"));
+  EXPECT_EQ(kSample + 1, test::LastHistogramSample("Name2"));
+  EXPECT_EQ(kSample + 2, test::LastHistogramSample("Name3"));
+}
+
 TEST(MetricsTest, RtcHistogramSparse_NonConstantNameWorks) {
   test::ClearHistograms();
   AddSparseSample("Name1", kSample);