Add UMA histograms for Google cached copy experiment on network error interstitial

chrome/renderer/net/net_error_helper.cc

 // Copyright (c) 2013 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/renderer/net/net_error_helper.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/i18n/rtl.h"
@@ skipping 149 matching lines @@
 void NetErrorHelper::TrackClick(int tracking_id) {
   core_->TrackClick(tracking_id);
 }
 
 void NetErrorHelper::GenerateLocalizedErrorPage(
     const blink::WebURLError& error,
     bool is_failed_post,
     scoped_ptr<ErrorPageParams> params,
     bool* reload_button_shown,
     bool* show_saved_copy_button_shown,
+    bool* show_cached_copy_button_shown,
+    bool* show_cached_page_button_shown,
     std::string* error_html) const {
   error_html->clear();
 
   int resource_id = IDR_NET_ERROR_HTML;
   const base::StringPiece template_html(
       ResourceBundle::GetSharedInstance().GetRawDataResource(resource_id));
   if (template_html.empty()) {
     NOTREACHED() << "unable to load template.";
   } else {
     base::DictionaryValue error_strings;
     LocalizedError::GetStrings(error.reason, error.domain.utf8(),
                                error.unreachableURL, is_failed_post,
                                error.staleCopyInCache,
                                RenderThread::Get()->GetLocale(),
                                render_frame()->GetRenderView()->
                                    GetAcceptLanguages(),
                                params.Pass(), &error_strings);
     *reload_button_shown = error_strings.Get("reloadButton", NULL);
     *show_saved_copy_button_shown =
         error_strings.Get("showSavedCopyButton", NULL);
 
+    bool show_cache_copy_button_default_label;
+    bool showing_cache_copy_experiment =
+        error_strings.GetBoolean("cacheButton.defaultLabel",
+        &show_cache_copy_button_default_label);
+    if (showing_cache_copy_experiment) {
+      if (show_cache_copy_button_default_label) {
+        *show_cached_copy_button_shown = false;
+        *show_cached_page_button_shown = true;
+      } else {
+        *show_cached_page_button_shown = false;
+        *show_cached_copy_button_shown = true;
+      }
+    }
     // "t" is the id of the template's root node.
     *error_html = webui::GetTemplatesHtml(template_html, &error_strings, "t");
   }
 }
 
 void NetErrorHelper::LoadErrorPageInMainFrame(const std::string& html,
                                               const GURL& failed_url) {
   blink::WebView* web_view = render_frame()->GetRenderView()->GetWebView();
   if (!web_view)
     return;
@@ skipping 133 matching lines @@
       success ? data : "",
       render_frame()->GetRenderView()->GetAcceptLanguages(),
       base::i18n::IsRTL());
 }
 
 void NetErrorHelper::OnTrackingRequestComplete(
     const blink::WebURLResponse& response,
     const std::string& data) {
   tracking_fetcher_.reset();
 }