Move preference MACs to the protected preference stores.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 6b4df83da34e2b5fe0efaebc5c3dbe254b35063b..0f028518f042d0494b39b9633e04d067e6ecb261 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -2394,11 +2394,6 @@ const char kWatchdogExtensionActive[] =
 const char kWatchdogExtensionActiveOld[] =
     "profile.extensions.activity_log.watchdog_extension_active";
 
-// A dictionary pref which maps profile names to dictionary values which hold
-// hashes of profile prefs that we track to detect changes that happen outside
-// of Chrome.
-const char kProfilePreferenceHashes[] = "profile.preference_hashes";
-
 #if defined(OS_ANDROID)
 // A list of partner bookmark rename/remove mappings.
 // Each list item is a dictionary containing a "url", a "provider_title" and