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 17f3723ca554170b330b3cc6e4f2d92a634d9f28..e88b160c506944790101e6e10a7e3cbea7cf1c39 100644
--- a/chrome/browser/profiles/profile.cc
+++ b/chrome/browser/profiles/profile.cc
@@ -60,6 +60,10 @@ TestingProfile* Profile::AsTestingProfile() {
   return NULL;
 }
 
+PrefService* Profile::GetZoomLevelPrefs() {
+  return NULL;
+}
+
 Profile::Delegate::~Delegate() {
 }
 
@@ -137,11 +141,11 @@ void Profile::RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
       std::string(),
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterDoublePref(
-      prefs::kDefaultZoomLevel,
+      prefs::kProfileDefaultZoomLevel,
       0.0,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterDictionaryPref(
-      prefs::kPerHostZoomLevels,
+      prefs::kProfilePerHostZoomLevels,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterStringPref(
       prefs::kDefaultApps,