Add Sparse Histogram Support to metricsPrivate

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

 // Copyright (c) 2012 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.
 
 // metrics api test
 // browser_tests.exe --gtest_filter=ExtensionApiTest.Metrics
 
 // Any changes to the logging done in these functions should be matched
 // with the checks done in IN_PROC_BROWSER_TEST_F(ExtensionApiTest, Metrics).
 // See metrics_apitest.cc.
@@ skipping 25 matching lines @@
       'max': 200,
       'buckets': 50
     }, 42);
 
     chrome.metricsPrivate.recordPercentage('test.h.3', 42);
     chrome.metricsPrivate.recordPercentage('test.h.3', 42);
 
     chrome.test.succeed();
   },
 
+  function recordSparseValue() {
+    chrome.metricsPrivate.recordSparseValue('test.sparse.1', 42);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.2', 42);
+    chrome.metricsPrivate.recordSparseValue('test.sparse.2', 42);

[Ilya Sherman, 2014/03/26 22:02:03]

It would be nice to verify that more buckets than just bucket #42 can be emitted
to.

[robliao, 2014/03/26 22:30:50]

Done.

+
+    chrome.test.succeed();
+  },
+
   function recordTimes() {
     chrome.metricsPrivate.recordTime('test.time', 42);
     chrome.metricsPrivate.recordMediumTime('test.medium.time', 42 * 1000);
     chrome.metricsPrivate.recordLongTime('test.long.time', 42 * 1000 * 60);
 
     chrome.test.succeed();
   },
 
   function recordCounts() {
     chrome.metricsPrivate.recordCount('test.count', 420000);
@@ skipping 76 matching lines @@
     // This one should be rejected because the bucket count is different.
     // We check for sample count == 2 in metrics_apitest.cc
     chrome.metricsPrivate.recordValue(log2, 42);
     chrome.metricsPrivate.recordValue(log1, 42);
 
     chrome.test.succeed();
   },
 
 ]);