Measuring data use of different ModelTypes in Sync Service.

sync/engine/commit.cc

Index: sync/engine/commit.cc
diff --git a/sync/engine/commit.cc b/sync/engine/commit.cc
index f607be4c8b4e91499e2d1184c9c8d491d6b0d7ba..a0ed654393dd984a4e7f3eb6c6ff473be12ddc56 100644
--- a/sync/engine/commit.cc
+++ b/sync/engine/commit.cc
@@ -4,6 +4,7 @@
 
 #include "sync/engine/commit.h"
 
+#include "base/metrics/sparse_histogram.h"
 #include "base/trace_event/trace_event.h"
 #include "sync/engine/commit_contribution.h"
 #include "sync/engine/commit_processor.h"
@@ -14,6 +15,13 @@
 #include "sync/internal_api/public/events/commit_response_event.h"
 #include "sync/sessions/sync_session.h"
 
+#define UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE(name, sample, value)     \
+  do {                                                                  \
+    base::HistogramBase* histogram = base::SparseHistogram::FactoryGet( \
+        name, base::HistogramBase::kUmaTargetedHistogramFlag);          \
+    histogram->AddCount(sample, value);                                 \
+  } while (0)
+
 namespace syncer {
 
 Commit::Commit(ContributionMap contributions,
@@ -70,11 +78,19 @@ Commit* Commit::Init(
       enabled_types,
       commit_message);
 
+  int previous_message_size = message.ByteSize();
   // Finally, serialize all our contributions.
   for (std::map<ModelType, CommitContribution*>::const_iterator it =
            contributions.begin();
        it != contributions.end(); ++it) {
     it->second->AddToCommitMessage(&message);
+    int new_message_part_size = message.ByteSize()-previous_message_size;

[bengr, 2015/08/07 17:13:37]

I have no idea what new_message_part_size means. Use a better name.

[amohammadkhan, 2015/08/07 18:52:30]

Done.

+    if (new_message_part_size > 0)

[bengr, 2015/08/07 17:13:37]

Add curly braces.

[amohammadkhan, 2015/08/07 18:52:30]

Done.

+      UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE("DataUse.Sync.Upload.Bytes",
+                                             it->first,
+                                             new_message_part_size);
+    UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE("DataUse.Sync.Upload.Bytes",
+                                           it->first, 1);
   }
 
   // If we made it this far, then we've successfully prepared a commit message.