[Cleanup] Remove some expired omnibox field trials.

components/omnibox/browser/omnibox_field_trial.h

Index: components/omnibox/browser/omnibox_field_trial.h
diff --git a/components/omnibox/browser/omnibox_field_trial.h b/components/omnibox/browser/omnibox_field_trial.h
index 4a676ff382c82507dd4bfb42394b4c9c8b5bd1f9..51be5dce5fa5a1e91721abbe50acc20541249185 100644
--- a/components/omnibox/browser/omnibox_field_trial.h
+++ b/components/omnibox/browser/omnibox_field_trial.h
@@ -111,14 +111,6 @@ class OmniboxFieldTrial {
     EMPHASIZE_NEVER = 3
   };
 
-  // Activates all dynamic field trials.  The main difference between
-  // the autocomplete dynamic and static field trials is that the former
-  // don't require any code changes on the Chrome side as they are controlled
-  // on the server side.  Chrome binary simply propagates all necessary
-  // information through the X-Client-Data header.
-  // This method may be called multiple times.
-  static void ActivateDynamicTrials();
-
   // ---------------------------------------------------------
   // For any experiment that's part of the bundled omnibox field trial.