Measuring data use of different ModelTypes in Sync Service.

sync/engine/directory_update_handler.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/engine/directory_update_handler.h"
 
+#include "base/metrics/sparse_histogram.h"
 #include "sync/engine/conflict_resolver.h"
 #include "sync/engine/process_updates_util.h"
 #include "sync/engine/update_applicator.h"
 #include "sync/sessions/directory_type_debug_info_emitter.h"
 #include "sync/syncable/directory.h"
 #include "sync/syncable/model_neutral_mutable_entry.h"
 #include "sync/syncable/syncable_model_neutral_write_transaction.h"
 #include "sync/syncable/syncable_write_transaction.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 {
 
 using syncable::SYNCER;
 
 DirectoryUpdateHandler::DirectoryUpdateHandler(
     syncable::Directory* dir,
     ModelType type,
     scoped_refptr<ModelSafeWorker> worker,
     DirectoryTypeDebugInfoEmitter* debug_info_emitter)
   : dir_(dir),
@@ skipping 13 matching lines @@
   syncable::ModelNeutralWriteTransaction trans(FROM_HERE, SYNCER, dir_);
   dir_->GetDataTypeContext(&trans, type_, context);
 }
 
 SyncerError DirectoryUpdateHandler::ProcessGetUpdatesResponse(
     const sync_pb::DataTypeProgressMarker& progress_marker,
     const sync_pb::DataTypeContext& mutated_context,
     const SyncEntityList& applicable_updates,
     sessions::StatusController* status) {
   syncable::ModelNeutralWriteTransaction trans(FROM_HERE, SYNCER, dir_);
+  if (progress_marker.ByteSize() > 0) {
+    UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE("DataUse.Sync.ProgressMarker.Bytes",
+                                           ModelTypeToHistogramInt(type_),
+                                           progress_marker.ByteSize());
+  }
   if (mutated_context.has_context()) {
     sync_pb::DataTypeContext local_context;
     dir_->GetDataTypeContext(&trans, type_, &local_context);
 
     // Only update the local context if it is still relevant. If the local
     // version is higher, it means a local change happened while the mutation
     // was in flight, and the local context takes priority.
     if (mutated_context.version() >= local_context.version() &&
         local_context.context() != mutated_context.context()) {
       dir_->SetDataTypeContext(&trans, type_, mutated_context);
@@ skipping 223 matching lines @@
               new_gc_directive.version_watermark())) {
     ExpireEntriesByVersion(dir_, trans, type_,
                            new_gc_directive.version_watermark());
   }
 
   cached_gc_directive_.reset(
       new sync_pb::GarbageCollectionDirective(new_gc_directive));
 }
 
 }  // namespace syncer