Added pref for snapshot document collapsed state

chrome/common/pref_names.h

Index: chrome/common/pref_names.h
diff --git a/chrome/common/pref_names.h b/chrome/common/pref_names.h
index da61b8d252a394c1440fdfdddcb15683d448e9c0..89d4f5a274fdc1785fe581c6c3fb98ba473d5bcf 100644
--- a/chrome/common/pref_names.h
+++ b/chrome/common/pref_names.h
@@ -566,17 +566,19 @@ extern const char kExtensionInstallDenyList[];
 extern const char kExtensionInstallForceList[];
 extern const char kExtensionStorageGarbageCollect[];
 
-extern const char kNtpTipsResourceServer[];
-
+extern const char kNtpAppPageNames[];
 extern const char kNtpCollapsedForeignSessions[];
+extern const char kNtpCollapsedRecentlyClosedTabs[];
+extern const char kNtpCollapsedSnapshotDocument[];
+extern const char kNtpCollapsedSyncPromo[];
+extern const char kNtpDateResourceServer[];
 extern const char kNtpMostVisitedURLsBlacklist[];
+extern const char kNtpPromoDesktopSessionFound[];
 extern const char kNtpPromoResourceCacheUpdate[];
-extern const char kNtpDateResourceServer[];
 extern const char kNtpShownBookmarksFolder[];
 extern const char kNtpShownPage[];
-extern const char kNtpPromoDesktopSessionFound[];
+extern const char kNtpTipsResourceServer[];
 extern const char kNtpWebStoreEnabled[];
-extern const char kNtpAppPageNames[];
 
 extern const char kDevToolsAdbKey[];
 extern const char kDevToolsDisabled[];