Introduce a field trial for Instant.

chrome/browser/ui/webui/options/browser_options_handler.h

Index: chrome/browser/ui/webui/options/browser_options_handler.h
diff --git a/chrome/browser/ui/webui/options/browser_options_handler.h b/chrome/browser/ui/webui/options/browser_options_handler.h
index 097ee00e830b6c92945bbcb423077f1f68ee7b02..12e76d8894621e0898439c20d68b33f37e057696 100644
--- a/chrome/browser/ui/webui/options/browser_options_handler.h
+++ b/chrome/browser/ui/webui/options/browser_options_handler.h
@@ -90,6 +90,13 @@ class BrowserOptionsHandler : public OptionsPageUIHandler,
   // Notifies any listeners interested in this event.  |args| is ignored.
   void ToggleShowBookmarksBar(const ListValue* args);
 
+  // Enables/disables instant.
+  void EnableInstant(const ListValue* args);
+  void DisableInstant(const ListValue* args);
+
+  // Called to request information about the Instant field trial.
+  void IsInstantFieldTrialExperimentGroup(const ListValue* args);
+
   // Returns the string ID for the given default browser state.
   int StatusStringIdForState(ShellIntegration::DefaultWebClientState state);