Persist the extension omnibox default suggestion to Prefs.

chrome/browser/extensions/extension_prefs.h

Index: chrome/browser/extensions/extension_prefs.h
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index c3791f9d74b4b2bd6e500f6fed00e54a42b4f103..488a9f7933bc0027cc5169c6798eba7264dbf484 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -26,6 +26,7 @@ class URLPatternSet;
 
 namespace extensions {
 struct AlarmPref;
+struct ExtensionOmniboxSuggestion;
 }
 
 // Class for managing global and per-extension preferences.
@@ -271,6 +272,13 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer,
   void SetRegisteredAlarms(const std::string& extension_id,
                            const std::vector<extensions::AlarmPref>& alarms);
 
+  // Controls the omnibox default suggestion as set by the extension.
+  extensions::ExtensionOmniboxSuggestion GetOmniboxDefaultSuggestion(
+      const std::string& extension_id);
+  void SetOmniboxDefaultSuggestion(
+      const std::string& extension_id,
+      const extensions::ExtensionOmniboxSuggestion& suggestion);
+
   // Returns true if the user enabled this extension to be loaded in incognito
   // mode.
   bool IsIncognitoEnabled(const std::string& extension_id);