Introduce notification_helper_constants.* to improve code consistency

Bug: 734095
Change-Id: Idf5637bb57a7cbfb0b5831cf99e45806d8a9abc6
Reviewed-on: https://chromium-review.googlesource.com/1026972
Reviewed-by: John Abd-El-Malek <[email protected]>
Commit-Queue: Xi Cheng <[email protected]>
Cr-Commit-Position: refs/heads/master@{#553451}
diff --git a/chrome/browser/DEPS b/chrome/browser/DEPS
index 1c0a53a..586d66a9 100644
--- a/chrome/browser/DEPS
+++ b/chrome/browser/DEPS
@@ -6,6 +6,7 @@
   "+chrome/grit",
   "+chrome/install_static",
   "+chrome/installer/util",
+  "+chrome/notification_helper/notification_helper_constants.h",
   "+chrome/services/file_util/public",
   "+chrome/services/media_gallery_util/public",
   "+chrome/services/printing/public",