Add Desktop iOS promotion logging to chrome ios app.

ios/chrome/browser/pref_names.cc

Index: ios/chrome/browser/pref_names.cc
diff --git a/ios/chrome/browser/pref_names.cc b/ios/chrome/browser/pref_names.cc
index 0f75891881a2994a01b2fc19aac88864a4f13d39..5fccd808e994612005d6cbf21c10da80aff25f9e 100644
--- a/ios/chrome/browser/pref_names.cc
+++ b/ios/chrome/browser/pref_names.cc
@@ -139,4 +139,22 @@ const char kOmniboxGeolocationLastAuthorizationAlertVersion[] =
 const char kRateThisAppDialogLastShownTime[] =
     "ios.ratethisapp.dialog_last_shown_time";
 
+// Integer which indicates which desktop ios promotion initiated sending the SMS
+// to the user.
+const char kDesktopIOSPromotionSMSEntryPoint[] =
+    "ios.desktop_ios_promo_sms_entrypoint";
+
+// Integer Which indicates which desktop ios promotions did the user see.
+const char kDesktopIOSPromotionShownEntryPoints[] =
+    "ios.desktop_ios_promo_shown_entrypoints";
+
+// Last desktop ios promotion impression (If SMS was sent it's the time of
+// sending the SMS).
+const char kDesktopIOSPromotionLastImpression[] =
+    "ios.desktop_ios_promo_last_impression";
+
+// True if the user see the promotion, get sms, install and sign into
+// chrome ios.
+const char kDesktopIOSPromotionDone[] = "ios.desktop_ios_promo_done";
+
 }  // namespace prefs