[NTP4] Experiment for adding Chrome Web Store link to footer.

chrome/common/extensions/extension_constants.h

Index: chrome/common/extensions/extension_constants.h
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index ad6981b771484daa3f91d20b37beb73efbabd363..cf9f16eb547c309bfdd30a1b37594d1f602d27b5 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -446,6 +446,9 @@ namespace extension_misc {
     // feature that let you make desktop shortcuts from the file menu.
     APP_LAUNCH_CMD_LINE_APP_LEGACY,
 
+    // User clicked web store link on the NTP footer.
+    APP_LAUNCH_NTP_WEBSTORE_FOOTER,
+
     APP_LAUNCH_BUCKET_BOUNDARY,
     APP_LAUNCH_BUCKET_INVALID
   };