reretry ValueMetric implementation and pulling mechanism

Note:
This is for value metric. The default operations is sum the diffs.
The test uses kernel wake lock, which also needs dimension by kernel
wake lock name.

The test is a bit cumbersome as it needs StatsCompanionService to do
the alarm, which is not exact alarm.

The internal state of a slice of bucket would look something like this:

4:ipc0000005e_727_android.hardwar
0      0
4:SensorService_wakelock
40      64
4:ipc0000005c_727_android.hardwar
...

Test: manual test on device.
Change-Id: I2ed0ac7d3c5fcba8b7611d46f38a38ffd8bdc92a
diff --git a/cmds/statsd/src/StatsService.cpp b/cmds/statsd/src/StatsService.cpp
index a856a27..edb1a0f 100644
--- a/cmds/statsd/src/StatsService.cpp
+++ b/cmds/statsd/src/StatsService.cpp
@@ -65,7 +65,6 @@
 StatsService::StatsService(const sp<Looper>& handlerLooper)
     : mAnomalyMonitor(new AnomalyMonitor(2))  // TODO: Put this comment somewhere better
 {
-    mStatsPullerManager = new StatsPullerManager();
     mUidMap = new UidMap();
     mConfigManager = new ConfigManager();
     mProcessor = new StatsLogProcessor(mUidMap, [this](const vector<uint8_t>& log) {
@@ -374,7 +373,7 @@
 
 status_t StatsService::cmd_print_pulled_metrics(FILE* out, const Vector<String8>& args) {
     int s = atoi(args[1].c_str());
-    auto stats = mStatsPullerManager->Pull(s);
+    auto stats = m_stats_puller_manager.Pull(s, time(nullptr));
     for (const auto& it : stats) {
         fprintf(out, "Pull from %d: %s\n", s, it->ToString().c_str());
     }
@@ -441,8 +440,9 @@
                                          "Only system uid can call informPollAlarmFired");
     }
 
+    m_stats_puller_manager.OnAlarmFired();
+
     if (DEBUG) ALOGD("StatsService::informPollAlarmFired succeeded");
-    // TODO: determine what services to poll and poll (or ask StatsCompanionService to poll) them.
 
     return Status::ok();
 }