Prerender: Remove deprecated prerender experiment histograms.

chrome/browser/predictors/autocomplete_action_predictor.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/predictors/autocomplete_action_predictor.h"
 
 #include <math.h>
 #include <stddef.h>
 
 #include <vector>
@@ skipping 228 matching lines @@
 
   // Abandon the current prerender. If it is to be used, it will be used very
   // soon, so use the lower timeout.
   if (prerender_handle_) {
     prerender_handle_->OnNavigateAway();
     // Don't release |prerender_handle_| so it is canceled if it survives to the
     // next StartPrerendering call.
   }
 
   UMA_HISTOGRAM_BOOLEAN(
-      base::StringPrintf("Prerender.OmniboxNavigationsCouldPrerender%s",
-                         prerender::PrerenderManager::GetModeString()).c_str(),
+      "Prerender.OmniboxNavigationsCouldPrerender",
       prerender::IsOmniboxEnabled(profile_));
 
   const AutocompleteMatch& match = log.result.match_at(log.selected_index);
   const GURL& opened_url = match.destination_url;
   const base::string16 lower_user_text(base::i18n::ToLower(log.text));
 
   // Traverse transitional matches for those that have a user_text that is a
   // prefix of |lower_user_text|.
   std::vector<AutocompleteActionPredictorTable::Row> rows_to_add;
   std::vector<AutocompleteActionPredictorTable::Row> rows_to_update;
@@ skipping 328 matching lines @@
 AutocompleteActionPredictor::TransitionalMatch::TransitionalMatch() {
 }
 
 AutocompleteActionPredictor::TransitionalMatch::TransitionalMatch(
     const TransitionalMatch& other) = default;
 
 AutocompleteActionPredictor::TransitionalMatch::~TransitionalMatch() {
 }
 
 }  // namespace predictors