[ImportantSites] Implementing dialog level blacklisting and blacklist expiration

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 7b14c9a6ea83e6f322a32cfadd4009a4f8552076..06a71860292f6bb08f6ac31e37bfc83608e2ac70 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -180,6 +180,10 @@ const char kSupervisedUserSharedSettings[] = "profile.managed.shared_settings";
 // (currently the name).
 const char kSupervisedUserWhitelists[] = "profile.managed.whitelists";
 
+// Stores information about the important sites dialog, including the time and
+// frequency it has been ignored.
+const char kImportantSitesDialogHistory = "important_sites_dialog";
+
 // The application locale.
 // For OS_CHROMEOS we maintain the kApplicationLocale property in both local
 // state and the user's profile.  The global property determines the locale of