Track size of files serialized by the JsonPrefStore.

base/prefs/json_pref_store.cc

 // Copyright (c) 2012 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 "base/prefs/json_pref_store.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/file_util.h"
+#include "base/files/file_path.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/metrics/histogram.h"
 #include "base/prefs/pref_filter.h"
 #include "base/sequenced_task_runner.h"
+#include "base/strings/string_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/values.h"
 
 namespace {
 
 // Some extensions we'll tack on to copies of the Preferences files.
 const base::FilePath::CharType* kBadExtension = FILE_PATH_LITERAL("bad");
 
 // Differentiates file loading between origin thread and passed
 // (aka file) thread.
@@ skipping 353 matching lines @@
 JsonPrefStore::~JsonPrefStore() {
   CommitPendingWrite();
 }
 
 bool JsonPrefStore::SerializeData(std::string* output) {
   if (pref_filter_)
     pref_filter_->FilterSerializeData(prefs_.get());
 
   JSONStringValueSerializer serializer(output);
   serializer.set_pretty_print(true);
-  return serializer.Serialize(*prefs_);
+  bool result = serializer.Serialize(*prefs_);
+
+  if (result) {
+    std::string spaceless_basename;
+    base::ReplaceChars(path_.BaseName().MaybeAsASCII(), " ", "_",
+                       &spaceless_basename);
+
+    // The histogram below is an expansion of the UMA_HISTOGRAM_COUNTS_10000
+    // macro adapted to allow for a dynamically suffixed histogram name.
+    // Note: The factory creates and owns the histogram.
+    base::HistogramBase* histogram =
+        base::LinearHistogram::FactoryGet(
+            "Settings.JsonDataSizeKilobytes." + spaceless_basename,
+            1,
+            10000,
+            50,
+            base::HistogramBase::kUmaTargetedHistogramFlag);
+    histogram->Add(static_cast<int>(output->size()) / 1024);
+  }
+
+  return result;
 }
 
 void JsonPrefStore::FinalizeFileRead(bool initialization_successful,
                                      scoped_ptr<base::DictionaryValue> prefs,
                                      bool schedule_write) {
   filtering_in_progress_ = false;
 
   if (!initialization_successful) {
     FOR_EACH_OBSERVER(PrefStore::Observer,
                       observers_,
@@ skipping 10 matching lines @@
 
   if (error_delegate_ && read_error_ != PREF_READ_ERROR_NONE)
     error_delegate_->OnError(read_error_);
 
   FOR_EACH_OBSERVER(PrefStore::Observer,
                     observers_,
                     OnInitializationCompleted(true));
 
   return;
 }