Connect SparseHistogram with the rest of stats system

With this CL, SparseHistogram is usable with SparseHistogram::FactoryGet.
Next step is to implement a Histogram like macro and implement WriteHTMLGraph
and WriteAscii to have a nice output.

BUG=139612


Review URL: https://chromiumcodereview.appspot.com/12207058

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@185451 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: cc7dec210cd2a325e65eaab44e4569846de72862
diff --git a/dbus/signal_sender_verification_unittest.cc b/dbus/signal_sender_verification_unittest.cc
index d66067f..2f2eb44 100644
--- a/dbus/signal_sender_verification_unittest.cc
+++ b/dbus/signal_sender_verification_unittest.cc
@@ -182,7 +182,7 @@
 TEST_F(SignalSenderVerificationTest, TestSignalRejected) {
   // To make sure the histogram instance is created.
   UMA_HISTOGRAM_COUNTS("DBus.RejectedSignalCount", 0);
-  base::Histogram* reject_signal_histogram =
+  base::HistogramBase* reject_signal_histogram =
         base::StatisticsRecorder::FindHistogram("DBus.RejectedSignalCount");
   scoped_ptr<base::HistogramSamples> samples1(
       reject_signal_histogram->SnapshotSamples());