Adding multi layer aggregation in DurationMetric

Newly supported metrics examples:

1) Compute [Total|Max] duration of [an app] holding [ANY] wake lock while [this app] is in
   [background] and [screen off], bucket size 30seconds, and slice output by uid.

2) Compute [Total|Max] duration of [ANY app] holding [ANY] wake lock while [this app] is in
   [background] and [screen off], bucket size 30 seconds.

+ DurationMetric proto has a "what" which is a SimpleCondition. It defines the atom level start
  and stop of the duration timer, and it has its atom dimension. e.g., for wake locks, the atom
  dimensions wil be uid and wl name.

+ Now dimension is explicitly specified in SimpleCondition proto instead of inferred from the "link"

+ Added support for "Or" and "Max" through 2 layers of aggregation.

TODO: (1) The way we track slicedCondition in duration metric is not efficient. optimize!
      (2) The output dimension should all use int32 instead of KeyMatcher. Fix in a future cl.

Test: Added some unit tests using gmock. Will add more unit tests.

Change-Id: I58a827624f01f9a54fcb80709c4de4ff94a8bc67
diff --git a/cmds/statsd/src/metrics/MetricsManager.cpp b/cmds/statsd/src/metrics/MetricsManager.cpp
index 4fa3965..d1df8aa 100644
--- a/cmds/statsd/src/metrics/MetricsManager.cpp
+++ b/cmds/statsd/src/metrics/MetricsManager.cpp
@@ -74,6 +74,7 @@
     }
 
     int tagId = event.GetTagId();
+    uint64_t eventTime = event.GetTimestampNs();
     if (mTagIds.find(tagId) == mTagIds.end()) {
         // not interesting...
         return;
@@ -124,13 +125,14 @@
                 // metric cares about non sliced condition, and it's changed.
                 // Push the new condition to it directly.
                 if (!mAllMetricProducers[metricIndex]->isConditionSliced() && changedCache[i]) {
-                    mAllMetricProducers[metricIndex]->onConditionChanged(conditionCache[i]);
+                    mAllMetricProducers[metricIndex]->onConditionChanged(conditionCache[i],
+                                                                         eventTime);
                     // metric cares about sliced conditions, and it may have changed. Send
                     // notification, and the metric can query the sliced conditions that are
                     // interesting to it.
                 } else if (mAllMetricProducers[metricIndex]->isConditionSliced() &&
                            slicedChangedCache[i]) {
-                    mAllMetricProducers[metricIndex]->onSlicedConditionMayChange();
+                    mAllMetricProducers[metricIndex]->onSlicedConditionMayChange(eventTime);
                 }
             }
         }