Improve profile stats performace.

components/prefs/pref_service.cc

Index: components/prefs/pref_service.cc
diff --git a/components/prefs/pref_service.cc b/components/prefs/pref_service.cc
index 6858839110b158b139c7e68fed680e5f50ddeb75..4ebea533478d97c4b6fa87b0f41abfae99dd0f61 100644
--- a/components/prefs/pref_service.cc
+++ b/components/prefs/pref_service.cc
@@ -193,37 +193,27 @@ bool PrefService::HasPrefPath(const std::string& path) const {
   return pref && !pref->IsDefaultValue();
 }
 
-std::unique_ptr<base::DictionaryValue> PrefService::GetPreferenceValues()
-    const {
-  DCHECK(CalledOnValidThread());
-  std::unique_ptr<base::DictionaryValue> out(new base::DictionaryValue);
-  for (const auto& it : *pref_registry_) {
-    out->Set(it.first, GetPreferenceValue(it.first)->CreateDeepCopy());
-  }
-  return out;
-}
-
-std::unique_ptr<base::DictionaryValue>
-PrefService::GetPreferenceValuesOmitDefaults() const {
+void PrefService::IteratePreferenceValues(
+    base::RepeatingCallback<void(const std::string& key,
+                                 const base::Value& value)> callback) const {
   DCHECK(CalledOnValidThread());
-  std::unique_ptr<base::DictionaryValue> out(new base::DictionaryValue);
-  for (const auto& it : *pref_registry_) {
-    const Preference* pref = FindPreference(it.first);
-    if (pref->IsDefaultValue())
-      continue;
-    out->Set(it.first, pref->GetValue()->CreateDeepCopy());
-  }
-  return out;
+  for (const auto& it : *pref_registry_)
+    callback.Run(it.first, *GetPreferenceValue(it.first));
 }
 
-std::unique_ptr<base::DictionaryValue>
-PrefService::GetPreferenceValuesWithoutPathExpansion() const {
+std::unique_ptr<base::DictionaryValue> PrefService::GetPreferenceValues(
+    IncludeDefaults include_defaults) const {
   DCHECK(CalledOnValidThread());
   std::unique_ptr<base::DictionaryValue> out(new base::DictionaryValue);
   for (const auto& it : *pref_registry_) {
-    const base::Value* value = GetPreferenceValue(it.first);
-    DCHECK(value);
-    out->SetWithoutPathExpansion(it.first, value->CreateDeepCopy());
+    if (include_defaults == INCLUDE_DEFAULTS) {
+      out->Set(it.first, GetPreferenceValue(it.first)->CreateDeepCopy());
+    } else {
+      const Preference* pref = FindPreference(it.first);
+      if (pref->IsDefaultValue())
+        continue;
+      out->Set(it.first, pref->GetValue()->CreateDeepCopy());
+    }
   }
   return out;
 }