Add UMA to report Preferences File Corruption

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 d719e4bcb557861ecf22edcfe5e8f35604d7d861..c111cb5718bc65c60263133ca9cf7b1d31ef5d5f 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -2597,4 +2597,9 @@ const char kEnableDRM[] = "settings.privacy.drm_enabled";
 const char kWatchdogExtensionActive[] =
     "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";
+
 }  // namespace prefs