Settings Overides -- warn user when extensions override their NTP.

extensions/browser/extension_prefs.cc

Index: extensions/browser/extension_prefs.cc
diff --git a/extensions/browser/extension_prefs.cc b/extensions/browser/extension_prefs.cc
index 9a3933134cd069b64264deedd09cbc8c223592f7..e9b4a765facb73e3a9b1ca20767a5690a221f6dd 100644
--- a/extensions/browser/extension_prefs.cc
+++ b/extensions/browser/extension_prefs.cc
@@ -77,6 +77,7 @@ const char kPrefExternalAcknowledged[] = "ack_external";
 const char kPrefBlacklistAcknowledged[] = "ack_blacklist";
 const char kPrefWipeoutAcknowledged[] = "ack_wiped";
 const char kPrefSettingsBubbleAcknowledged[] = "ack_settings_bubble";
+const char kPrefNtpBubbleAcknowledged[] = "ack_ntp_bubble";
 
 // Indicates whether the external extension was installed during the first
 // run of this profile.
@@ -747,6 +748,19 @@ void ExtensionPrefs::SetSettingsApiBubbleBeenAcknowledged(
                       value ? base::Value::CreateBooleanValue(value) : NULL);
 }
 
+bool ExtensionPrefs::HasNtpOverriddenBubbleBeenAcknowledged(
+    const std::string& extension_id) {
+  return ReadPrefAsBooleanAndReturn(extension_id, kPrefNtpBubbleAcknowledged);
+}
+
+void ExtensionPrefs::SetNtpOverriddenBubbleBeenAcknowledged(
+    const std::string& extension_id,
+    bool value) {
+  UpdateExtensionPref(extension_id,
+                      kPrefNtpBubbleAcknowledged,
+                      value ? base::Value::CreateBooleanValue(value) : NULL);
+}
+
 bool ExtensionPrefs::SetAlertSystemFirstRun() {
   if (prefs_->GetBoolean(pref_names::kAlertsInitialized)) {
     return true;