Improve performance of registering font preferences

chrome/browser/prefs/pref_service.cc

Index: chrome/browser/prefs/pref_service.cc
diff --git a/chrome/browser/prefs/pref_service.cc b/chrome/browser/prefs/pref_service.cc
index cca8041c850284e277887d6be536316148ee68bd..79068885668c085549c03f1d0de2107545b796d2 100644
--- a/chrome/browser/prefs/pref_service.cc
+++ b/chrome/browser/prefs/pref_service.cc
@@ -471,6 +471,15 @@ void PrefService::RegisterStringPref(const char* path,
                      sync_status);
 }
 
+void PrefService::RegisterStringPrefIfNew(const char* path,
+                                          const std::string& default_value,
+                                     PrefSyncStatus sync_status) {
+  DCHECK(IsProfilePrefService(this));
+  RegisterPreferenceIfNew(path,
+                          Value::CreateStringValue(default_value),
+                          sync_status);
+  }
+
 void PrefService::RegisterFilePathPref(const char* path,
                                        const FilePath& default_value,
                                        PrefSyncStatus sync_status) {
@@ -779,19 +788,17 @@ void PrefService::RemovePrefObserver(const char* path,
   pref_notifier_->RemovePrefObserver(path, obs);
 }
 
-void PrefService::RegisterPreference(const char* path,
-                                     Value* default_value,
-                                     PrefSyncStatus sync_status) {
+void PrefService::RegisterNewPreference(const char* path,
+                                        Value* default_value,
+                                        PrefSyncStatus sync_status) {
+  // Note: The perfomance of this method is critical to startup performance,
+  // at least on Android, so do not introduce extra checks unless they are
+  // compiled out of official builds.
   DCHECK(CalledOnValidThread());
 
   // The main code path takes ownership, but most don't. We'll be safe.
   scoped_ptr<Value> scoped_value(default_value);
 
-  if (FindPreference(path)) {
-    NOTREACHED() << "Tried to register duplicate pref " << path;

[Bernhard Bauer, 2012/10/30 14:34:16]

Seeing as this is just a NOTREACHED (which would imply an internal error if it
happens), could we just change it to a DCHECK? That would improve the
performance at least for a Release build.

-    return;
-  }
-
   base::Value::Type orig_type = default_value->GetType();
   DCHECK(orig_type != Value::TYPE_NULL && orig_type != Value::TYPE_BINARY) <<
          "invalid preference type: " << orig_type;
@@ -821,6 +828,27 @@ void PrefService::RegisterPreference(const char* path,
     pref_sync_associator_->RegisterPref(path);
 }
 
+void PrefService::RegisterPreference(const char* path,
+                                     Value* default_value,
+                                     PrefSyncStatus sync_status) {
+  if (default_store_->GetType(path) != Value::TYPE_NULL) {
+    // Preference already exists
+    NOTREACHED() << "Tried to register duplicate pref " << path;
+    return;
+  }
+  RegisterNewPreference(path, default_value, sync_status);
+}
+
+void PrefService::RegisterPreferenceIfNew(const char* path,
+                                          Value* default_value,
+                                          PrefSyncStatus sync_status) {
+  if (default_store_->GetType(path) != Value::TYPE_NULL) {
+    // Preference already exists
+    return;
+  }
+  RegisterNewPreference(path, default_value, sync_status);
+}
+
 void PrefService::UnregisterPreference(const char* path) {
   DCHECK(CalledOnValidThread());