Remove AppListMixer field trial.

ui/app_list/search_controller.h

Index: ui/app_list/search_controller.h
diff --git a/ui/app_list/search_controller.h b/ui/app_list/search_controller.h
index 8ba61d2b9aae85db3b3fc754b49b5c2aaac28693..8df0d615a5195106459d735957f8d4d98fcba9bc 100644
--- a/ui/app_list/search_controller.h
+++ b/ui/app_list/search_controller.h
@@ -43,10 +43,7 @@ class APP_LIST_EXPORT SearchController {
                           int event_flags);
 
   // Adds a new mixer group. See Mixer::AddGroup.
-  size_t AddGroup(size_t max_results, double boost, double multiplier);
-
-  // Adds a new mixer group. See Mixer::AddOmniboxGroup.
-  size_t AddOmniboxGroup(size_t max_results, double boost, double multiplier);
+  size_t AddGroup(size_t max_results, double multiplier);
 
   // Takes ownership of |provider| and associates it with given mixer group.
   void AddProvider(size_t group_id, std::unique_ptr<SearchProvider> provider);