Update CountAnomalyTracker to handle slicing.

Re-added CountAnomalyTracker (under the name DiscreteAnomalyDetector).
It is now able to handle dimensions.

Test: unit test passed.

Change-Id: I133fcf6db99b9e305756f7ee5891c25f0f276348

bin/src/stats_util.h

diff --git a/bin/src/stats_util.h b/bin/src/stats_util.h
index a9507bf..e1d0ace 100644
--- a/bin/src/stats_util.h
+++ b/bin/src/stats_util.h
@@ -13,8 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#ifndef STATS_UTIL_H
-#define STATS_UTIL_H
+
+#pragma once
 
 #include "logd/LogReader.h"
 #include "storage/DropboxWriter.h"
@@ -22,6 +22,8 @@
 #include <log/logprint.h>
 #include "frameworks/base/cmds/statsd/src/statsd_config.pb.h"
 
+#include <unordered_map>
+
 namespace android {
 namespace os {
 namespace statsd {
@@ -33,6 +35,10 @@
 
 typedef std::map<std::string, HashableDimensionKey> ConditionKey;
 
+// TODO: For P, change int to int64_t.
+// TODO: Should HashableDimensionKey be marked here as const?
+typedef std::unordered_map<HashableDimensionKey, int> DimToValMap;
+
 EventMetricData parse(log_msg msg);
 
 int getTagId(log_msg msg);
@@ -41,5 +47,3 @@
 }  // namespace statsd
 }  // namespace os
 }  // namespace android
-
-#endif  // STATS_UTIL_H