Delay forcing natural scroll setting until after initial sync.

chrome/browser/chromeos/preferences.cc

Index: chrome/browser/chromeos/preferences.cc
===================================================================
--- chrome/browser/chromeos/preferences.cc	(revision 173817)
+++ chrome/browser/chromeos/preferences.cc	(working copy)
@@ -48,7 +48,9 @@
     : input_method_manager_(input_method_manager) {
 }
 
-Preferences::~Preferences() {}
+Preferences::~Preferences() {
+  prefs_->RemoveObserver(this);
+}
 
 // static
 void Preferences::RegisterUserPrefs(PrefService* prefs) {
@@ -387,6 +389,10 @@
 void Preferences::Init(PrefService* prefs) {
   InitUserPrefs(prefs);
 
+  // This causes OnIsSyncingChanged to be called when the value of

[sky, 2012/12/20 16:29:17]

OnIsSyncingChanged()

+  // PrefService::IsSyncing() changes.
+  prefs->AddObserver(this);
+
   // Initialize preferences to currently saved state.
   NotifyPrefChanged(NULL);
 
@@ -450,16 +456,9 @@
       UMA_HISTOGRAM_BOOLEAN("Touchpad.ThreeFingerSwipe.Started", enabled);
   }
   if (!pref_name || *pref_name == prefs::kNaturalScroll) {
-    // Force natural scroll to on if kNaturalScrollDefault is specified on the
-    // cmd line.
-    if (CommandLine::ForCurrentProcess()->HasSwitch(
-            switches::kNaturalScrollDefault) &&
-        !pref_name &&
-        !prefs_->GetUserPrefValue(prefs::kNaturalScroll)) {
-      natural_scroll_.SetValue(true);
-      DVLOG(1) << "Natural scroll forced to true";
-      UMA_HISTOGRAM_BOOLEAN("Touchpad.NaturalScroll.Forced", true);
-    }
+    // Force natural scroll default if we've sync'd and if the cmd line arg is
+    // set.
+    ForceNaturalScrollDefault();

[sky, 2012/12/20 16:29:17]

If you invoke ForceNaturalScrollDefault() here and IsSyncing is false won't you
ignore updating natural_scroll_ even though the user just changed the pref?

[xiyuan, 2012/12/20 17:07:49]

ForceNaturalScrollDefault just attempts to provide a default value based on
command line switch. The pref value handling is @463-469 below.

 
     const bool enabled = natural_scroll_.GetValue();
     DVLOG(1) << "Natural scroll set to " << enabled;
@@ -677,6 +676,23 @@
   }
 }
 
+void Preferences::OnIsSyncingChanged() {
+  DVLOG(1) << "OnIsSyncingChanged";
+  ForceNaturalScrollDefault();
+}
+
+void Preferences::ForceNaturalScrollDefault() {
+  DVLOG(1) << "ForceNaturalScrollDefault";
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kNaturalScrollDefault) &&
+      prefs_->IsSyncing() &&
+      !prefs_->GetUserPrefValue(prefs::kNaturalScroll)) {
+    DVLOG(1) << "Natural scroll forced to true";
+    natural_scroll_.SetValue(true);
+    UMA_HISTOGRAM_BOOLEAN("Touchpad.NaturalScroll.Forced", true);
+  }
+}
+
 void Preferences::SetLanguageConfigBoolean(const char* section,
                                            const char* name,
                                            bool value) {