Add an automatic settings reset banner.

chrome/browser/prefs/pref_hash_filter.cc

Index: chrome/browser/prefs/pref_hash_filter.cc
diff --git a/chrome/browser/prefs/pref_hash_filter.cc b/chrome/browser/prefs/pref_hash_filter.cc
index 1935708f9e22ca39964f2580d8dd402d1d39d9b9..98403edc19dc80f69d71f49cedd0570b108014ad 100644
--- a/chrome/browser/prefs/pref_hash_filter.cc
+++ b/chrome/browser/prefs/pref_hash_filter.cc
@@ -6,11 +6,15 @@
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/pref_service.h"
 #include "base/prefs/pref_store.h"
 #include "base/time/time.h"
 #include "base/values.h"
+#include "chrome/browser/browser_process.h"
 #include "chrome/browser/prefs/tracked/tracked_atomic_preference.h"
 #include "chrome/browser/prefs/tracked/tracked_split_preference.h"
+#include "chrome/common/pref_names.h"
 
 PrefHashFilter::PrefHashFilter(
     scoped_ptr<PrefHashStore> pref_hash_store,
@@ -63,6 +67,12 @@ PrefHashFilter::~PrefHashFilter() {
   DCHECK(changed_paths_.empty());
 }
 
+void PrefHashFilter::RegisterPrefs(PrefRegistrySimple* registry) {
+  // Register the pref that maintains state about the last time a reset event
+  // occurred. Used to decide whether to show UI.
+  registry->RegisterInt64Pref(prefs::kProfilePreferenceResetTime, 0L);
+}
+
 void PrefHashFilter::Initialize(PrefStore* pref_store) {
   UMA_HISTOGRAM_BOOLEAN(
       "Settings.TrackedPreferencesInitializedForUnloadedProfile", true);
@@ -82,10 +92,15 @@ void PrefHashFilter::Initialize(PrefStore* pref_store) {
 void PrefHashFilter::FilterOnLoad(base::DictionaryValue* pref_store_contents) {
   DCHECK(pref_store_contents);
   base::TimeTicks checkpoint = base::TimeTicks::Now();
+  bool did_reset = false;
   for (TrackedPreferencesMap::const_iterator it = tracked_paths_.begin();
        it != tracked_paths_.end(); ++it) {
-    it->second->EnforceAndReport(pref_store_contents);
+    did_reset = it->second->EnforceAndReport(pref_store_contents) || did_reset;

[gab, 2014/02/06 20:40:11]

I prefer

if (it->second->EnforceAndReport(pref_store_contents))
  did_reset = true;

The current form otherwise relies on the call being made by the order of the
boolean expression (i.e., if you swap the expressions on either side of the ||
this no longer works) which is harder to read IMO.

[robertshield, 2014/02/07 04:36:19]

Done.

   }
+
+  if (did_reset)
+    WriteResetEvent();
+
   // TODO(gab): Remove this histogram by Feb 21 2014; after sufficient timing
   // data has been gathered from the wild to be confident this doesn't
   // significantly affect startup.
@@ -124,3 +139,9 @@ void PrefHashFilter::FilterSerializeData(
                         base::TimeTicks::Now() - checkpoint);
   }
 }
+
+void PrefHashFilter::WriteResetEvent() {
+  g_browser_process->local_state()->SetInt64(
+      prefs::kProfilePreferenceResetTime,
+      base::Time::Now().ToInternalValue());
+}