Provide access to recommended pref values

chrome/browser/prefs/pref_value_store.cc

Index: chrome/browser/prefs/pref_value_store.cc
diff --git a/chrome/browser/prefs/pref_value_store.cc b/chrome/browser/prefs/pref_value_store.cc
index 8d59f4e52505854dff94849f63a080b5796752f3..0dda7dc045a842021bdc495645559c5b73a745f1 100644
--- a/chrome/browser/prefs/pref_value_store.cc
+++ b/chrome/browser/prefs/pref_value_store.cc
@@ -118,6 +118,20 @@ bool PrefValueStore::GetValue(const std::string& name,
   return false;
 }
 
+bool PrefValueStore::GetRecommendedValue(const std::string& name,
+                                         base::Value::Type type,
+                                         const Value** out_value) const {
+  *out_value = NULL;
+  if (!GetValueFromStore(name.c_str(), RECOMMENDED_STORE, out_value))
+    return false;
+  if (!(*out_value)->IsType(type)) {
+    LOG(WARNING) << "Expected type for " << name << " is " << type
+                 << " but got " << (*out_value)->GetType();
+    return false;
+   }

[Mattias Nissler (ping if slow), 2012/07/27 07:26:11]

indentation

[bartfab (slow), 2012/07/27 12:14:49]

Done.

+ return true;

[Mattias Nissler (ping if slow), 2012/07/27 07:26:11]

seems like the code in this function is essentially to loop body of GetValue()
above. Share?

[bartfab (slow), 2012/07/27 12:14:49]

Done.

+}
+
 void PrefValueStore::NotifyPrefChanged(
     const char* path,
     PrefValueStore::PrefStoreType new_store) {
@@ -130,6 +144,10 @@ void PrefValueStore::NotifyPrefChanged(
     pref_notifier_->OnPreferenceChanged(path);
     if (pref_sync_associator_)
       pref_sync_associator_->ProcessPrefChange(path);
+  // Always fire a notification when the recommended value changes, even if the
+  // effective value is unchanged.

[Mattias Nissler (ping if slow), 2012/07/27 07:26:11]

As discussed offline, maybe we want to just drop all the filtering. Can you
instrument a build and count the number of pref change notifications sent out w/
vs. w/out the filtering? I'd like to see some number on how much impact this
has.

[bartfab (slow), 2012/07/27 12:14:49]

Fresh profile: Start browser, visit google.com, shut down: 1489 pref change
notifications, 0 of these get filtered.

Existing profile: Start browser, visit google.com, visit settings page, shut
down: 1407 pref change notifications, 72 of these get filtered.

+  } else if (new_store == RECOMMENDED_STORE) {
+    pref_notifier_->OnPreferenceChanged(path);
   }
 }