[Home] Add personalized suggestions flag

Adds a feature that enables personalized suggestions when Chrome Home is
enabled. This value is then stored in a preference and read in
omnibox_field_trial.cc to determine whether personalized suggestions
are enabled.

Chrome Home has rather complex logic dictating whether or not it is
enabled, including an in-flight opt-in/opt-out that overwrites the base
feature value. Due to this, we cannot rely on a simple feature value in
omnibox_field_trial.

BUG=767273

Change-Id: I00e70c525244dd82e5f811ceeeab6a14c4e49994
Reviewed-on: https://chromium-review.googlesource.com/683295
Commit-Queue: Theresa <[email protected]>
Reviewed-by: Maria Khomenko <[email protected]>
Reviewed-by: Matthew Jones <[email protected]>
Reviewed-by: Mark Pearson <[email protected]>
Reviewed-by: Bernhard Bauer <[email protected]>
Cr-Commit-Position: refs/heads/master@{#505624}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 73e5cfd..6fb0bf4 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1593,6 +1593,11 @@
 const char kChromeHomeExpandButtonDescription[] =
     "Enables the expand button for Chrome Home.";
 
+const char kChromeHomePersonalizedOmniboxSuggestionsName[] =
+    "Chrome Home Personalized Omnibox Suggestions";
+const char kChromeHomePersonalizedOmniboxSuggestionsDescription[] =
+    "Enable personalized omnibox suggestions on focus for Chrome Home.";
+
 const char kChromeHomePromoName[] = "Chrome Home Promo";
 const char kChromeHomePromoDescription[] =
     "Force the Chrome Home promotion to show each time the browser restarts.";