[NTP::Push] Add BreakingNewsPushFeature flag to about::flags.

Bug: 
Change-Id: I0a82da04c6c197b41eb4ac2f9e0e5246c4b6261b
Reviewed-on: https://chromium-review.googlesource.com/599048
Commit-Queue: vitaliii <[email protected]>
Reviewed-by: Chris Pickel <[email protected]>
Cr-Commit-Position: refs/heads/master@{#491957}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 41398f9..ccf4a16 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -181,6 +181,9 @@
 extern const char kEnableAutofillCreditCardUploadCvcPromptName[];
 extern const char kEnableAutofillCreditCardUploadCvcPromptDescription[];
 
+extern const char kEnableBreakingNewsPushName[];
+extern const char kEnableBreakingNewsPushDescription[];
+
 extern const char kEnableBrotliName[];
 extern const char kEnableBrotliDescription[];