Record GCM received data message intervals in UMA

components/gcm_driver/gcm_stats_recorder_impl.cc

Index: components/gcm_driver/gcm_stats_recorder_impl.cc
diff --git a/components/gcm_driver/gcm_stats_recorder_impl.cc b/components/gcm_driver/gcm_stats_recorder_impl.cc
index 746d5e3fa801a69e5c9025c794aae8c926b996e4..5b215558d535fd4997ec9715633a851426dcc467 100644
--- a/components/gcm_driver/gcm_stats_recorder_impl.cc
+++ b/components/gcm_driver/gcm_stats_recorder_impl.cc
@@ -142,7 +142,9 @@ std::string GetUnregistrationStatusString(
 
 GCMStatsRecorderImpl::GCMStatsRecorderImpl()
     : is_recording_(false),
-      delegate_(NULL) {
+      delegate_(NULL),
+      clock_(new base::DefaultClock()),
+      last_data_message_received_timestamp_(0) {
 }
 
 GCMStatsRecorderImpl::~GCMStatsRecorderImpl() {
@@ -362,6 +364,14 @@ void GCMStatsRecorderImpl::RecordDataMessageReceived(
     ReceivedMessageType message_type) {
   if (to_registered_app)
     UMA_HISTOGRAM_COUNTS("GCM.DataMessageReceived", 1);
+
+  int64 new_timestamp = clock_->Now().ToTimeT();

[jianli, 2014/06/19 17:24:06]

Why not calling Time::Now()?

[juyik, 2014/07/15 23:42:12]

Done.

+  if (last_data_message_received_timestamp_ > 0) {

[fgorski, 2014/06/18 20:06:19]

will this trigger only after all of the messages that arrive during reconnect
are consumed, or after the first one?

We should let all of them pass, and start recording after a second (?) after
connection was made.

[fgorski, 2014/06/20 14:23:45]

Ju-Yi, given that the wake-up period during sleep is supposed to be 2 sec., why
don't we discard all of the 2 second bursts. We can update the name of the enum
to reflect that.

[juyik, 2014/07/15 23:42:12]

This is triggered every time a data message is consumed. So when
last_data_message_received_timestamp_ is zero, it means it is the first time
we've seen received message so there is no interval to think about.

[juyik, 2014/07/15 23:42:13]

Done. Collapsed all received data message within 2 seconds into 1 count. Changed
the UMA name as well. So when reconnection happens, we will receive a whole
bunch of data messages within 2 seconds and they count for 1 burst.

+    UMA_HISTOGRAM_COUNTS("GCM.DataMessageReceivedIntervalSeconds",

[fgorski, 2014/06/18 20:06:19]

please update histograms as well.

[juyik, 2014/07/15 23:42:13]

Updated the name.

+                         new_timestamp - last_data_message_received_timestamp_);
+  }
+  last_data_message_received_timestamp_ = new_timestamp;
+
   if (!is_recording_)
     return;
   if (!to_registered_app) {