Improve profile stats performace.

chrome/browser/profiles/profile_statistics_aggregator.cc

 // Copyright 2016 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 "chrome/browser/profiles/profile_statistics_aggregator.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "chrome/browser/bookmarks/bookmark_model_factory.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/password_manager/password_store_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/profiles/profile_statistics.h"
 #include "chrome/browser/profiles/profile_statistics_factory.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/bookmarks/browser/bookmark_node.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/password_manager/core/browser/password_store.h"
 #include "components/prefs/pref_service.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace {
 
+// Callback for each pref. Every one that should be counted as a changed
+// user pref will cause *count to be incremented.
+void AccumulatePrefStats(const PrefService* pref_service,
+                         int* count,
+                         const std::string& key,
+                         const base::Value& value) {
+  const PrefService::Preference* pref = pref_service->FindPreference(key);
+  // Skip all dictionaries, only want to count values.
+  if (!value.is_dict() && pref && pref->IsUserControlled() &&
+      !pref->IsDefaultValue())
+    ++(*count);
+}
+
 int CountBookmarksFromNode(const bookmarks::BookmarkNode* node) {
   int count = 0;
   if (node->is_url()) {
     ++count;
   } else {
     for (int i = 0; i < node->child_count(); ++i)
       count += CountBookmarksFromNode(node->GetChild(i));
   }
   return count;
 }
@@ skipping 170 matching lines @@
     StatisticsCallbackFailure(profiles::kProfileStatisticsBookmarks);
   }
 }
 
 ProfileStatisticsAggregator::ProfileStatValue
     ProfileStatisticsAggregator::CountPrefs() const {
   const PrefService* pref_service = profile_->GetPrefs();
 
   ProfileStatValue result;
   if (pref_service) {
-    std::unique_ptr<base::DictionaryValue> prefs =
-        pref_service->GetPreferenceValuesWithoutPathExpansion();
-
-    int count = 0;
-    for (base::DictionaryValue::Iterator it(*(prefs.get()));
-         !it.IsAtEnd(); it.Advance()) {
-      const PrefService::Preference* pref = pref_service->
-                                                FindPreference(it.key());
-      // Skip all dictionaries (which must be empty by the function call above).
-      if (it.value().GetType() != base::Value::Type::DICTIONARY &&
-        pref && pref->IsUserControlled() && !pref->IsDefaultValue()) {
-        ++count;
-      }
-    }
-
-    result.count = count;
+    pref_service->IteratePreferenceValues(base::BindRepeating(
+        &AccumulatePrefStats, pref_service, base::Unretained(&result.count)));
     result.success = true;
-  } else {
-    result.count = 0;
-    result.success = false;
   }
   return result;
 }