Add Sparse Histogram Support to metricsPrivate

chrome/test/data/extensions/api_test/metrics/test.js

Index: chrome/test/data/extensions/api_test/metrics/test.js
diff --git a/chrome/test/data/extensions/api_test/metrics/test.js b/chrome/test/data/extensions/api_test/metrics/test.js
index 619a14176027912e9a3716845a25e43861258545..77e84b29969d166926c248231d07db8685342308 100644
--- a/chrome/test/data/extensions/api_test/metrics/test.js
+++ b/chrome/test/data/extensions/api_test/metrics/test.js
@@ -43,6 +43,20 @@ chrome.test.runTests([
     chrome.test.succeed();
   },
 
+  function recordSparseValue() {
+    chrome.metricsPrivate.recordSparseValue('test.sparse.1', 42);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.2', 24);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.2', 24);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.3', 1);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.3', 2);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.3', 2);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.3', 3);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.3', 3);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.3', 3);
+
+    chrome.test.succeed();
+  },
+
   function recordTimes() {
     chrome.metricsPrivate.recordTime('test.time', 42);
     chrome.metricsPrivate.recordMediumTime('test.medium.time', 42 * 1000);