Initial CL for Data Saver (Flywheel) prompt when cellular network detected

chrome/browser/chromeos/status/data_promo_notification.h

Index: chrome/browser/chromeos/status/data_promo_notification.h
diff --git a/chrome/browser/chromeos/status/data_promo_notification.h b/chrome/browser/chromeos/status/data_promo_notification.h
index def5e8e6135d968df0063d2ecb1094e80f6ca2d6..5245393a085171fc6b6840e7b9b76aa662a791bc 100644
--- a/chrome/browser/chromeos/status/data_promo_notification.h
+++ b/chrome/browser/chromeos/status/data_promo_notification.h
@@ -34,8 +34,12 @@ class DataPromoNotification : public NetworkStateHandlerObserver {
   void NetworkPropertiesUpdated(const NetworkState* network) override;
   void DefaultNetworkChanged(const NetworkState* network) override;
 
-  // Shows 3G promo notification if needed.
-  void ShowOptionalMobileDataPromoNotification();
+  // Shows 3G promo notification if needed. |hotkey_debug| indicates that the
+  // NetworkPropertiesUpdated notification was generated by a debugging hotkey.
+  void ShowOptionalMobileDataPromoNotification(bool hotkey_debug);
+
+  // Show notification prompting user to install Data Saver extension.
+  bool ShowDataSaverNotification(bool hotkey_debug);
 
   // True if check for promo needs to be done, otherwise ignore it for the
   // current session.