Introduce ChromeZoomLevelPref, make zoom level prefs independent of profile prefs.

chrome/browser/profiles/profile.cc

Index: chrome/browser/profiles/profile.cc
diff --git a/chrome/browser/profiles/profile.cc b/chrome/browser/profiles/profile.cc
index 86326aa08254a89069e62c9a11413e3bb6e9d9d3..2bb1895654a2c090f65cffd3ad3b29d13a481a17 100644
--- a/chrome/browser/profiles/profile.cc
+++ b/chrome/browser/profiles/profile.cc
@@ -60,6 +60,10 @@ TestingProfile* Profile::AsTestingProfile() {
   return NULL;
 }
 
+chrome::ChromeZoomLevelPrefs* Profile::GetZoomLevelPrefs() {
+  return NULL;
+}
+
 Profile::Delegate::~Delegate() {
 }
 
@@ -136,11 +140,20 @@ void Profile::RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
       prefs::kSelectFileLastDirectory,
       std::string(),
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  // TODO(wjmaclean): remove the following two prefs once migration to per-
+  // partition zoom is complete.
   registry->RegisterDoublePref(
-      prefs::kDefaultZoomLevel,
+      prefs::kProfileDefaultZoomLevel,
       0.0,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterDictionaryPref(
+      prefs::kProfilePerHostZoomLevels,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+
+  registry->RegisterDictionaryPref(
+      prefs::kDefaultZoomLevel,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterDictionaryPref(
       prefs::kPerHostZoomLevels,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterStringPref(