[Home] Show opt-out survey snackbar when Chrome Home disabled

Adds a feature flag to show a snackbar prompting users to take a survey
the first time they opt out of Chrome Home.

BUG=773461

Change-Id: Ib5a4492e182e58b347f7677f60e762eae61a3f81
Reviewed-on: https://chromium-review.googlesource.com/713761
Commit-Queue: Theresa <[email protected]>
Reviewed-by: Ilya Sherman <[email protected]>
Reviewed-by: Matthew Jones <[email protected]>
Cr-Commit-Position: refs/heads/master@{#508234}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index a05289e..63ad0c0 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -983,6 +983,9 @@
 extern const char kChromeHomeDoodleName[];
 extern const char kChromeHomeDoodleDescription[];
 
+extern const char kChromeHomeOptOutSnackbarName[];
+extern const char kChromeHomeOptOutSnackbarDescription[];
+
 extern const char kChromeHomePersonalizedOmniboxSuggestionsName[];
 extern const char kChromeHomePersonalizedOmniboxSuggestionsDescription[];