Correctly record WebAPK install source for Launch.HomescreenSource

chrome/browser/android/shortcut_info.h

Index: chrome/browser/android/shortcut_info.h
diff --git a/chrome/browser/android/shortcut_info.h b/chrome/browser/android/shortcut_info.h
index 12c75336cf28da8681a1a1a000fea73278c37e8f..5626c8c6d0622a40efd8f59c5a02d34d5e763dbf 100644
--- a/chrome/browser/android/shortcut_info.h
+++ b/chrome/browser/android/shortcut_info.h
@@ -48,7 +48,11 @@ struct ShortcutInfo {
 
     // Used for WebAPK PWAs added via the banner.
     SOURCE_APP_BANNER_WEBAPK = 10,
-    SOURCE_COUNT = 11
+
+    // Used for WebAPK PWAs whose install source info was lost.
+    SOURCE_WEBAPK_UNKNOWN = 11,
+
+    SOURCE_COUNT = 12
   };
 
   explicit ShortcutInfo(const GURL& shortcut_url);