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

chrome/common/localized_error.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/common/localized_error.h"
 
 #include "base/command_line.h"
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
@@ skipping 880 matching lines @@
     suggestion->GetInteger("type", &type);
 
     if (type == kGoogleCachedCopySuggestionType) {
       base::string16 cache_url;
       suggestion->GetString("urlCorrection", &cache_url);
       int cache_tracking_id = -1;
       suggestion->GetInteger("trackingId", &cache_tracking_id);
 
       scoped_ptr<base::DictionaryValue> cache_button(new base::DictionaryValue);
 
+      // Google cache copy button label experiment.
       if (field_trial_exp_type_ == kCachedCopyButtonExpTypeCopy) {
         cache_button->SetString(
             "msg",
             l10n_util::GetStringUTF16(IDS_ERRORPAGES_BUTTON_SHOW_CACHED_COPY));
+        cache_button->SetBoolean("defaultLabel", false);
       } else {
         // Default to "Show cached page" button label.
         cache_button->SetString(
             "msg",
             l10n_util::GetStringUTF16(IDS_ERRORPAGES_BUTTON_SHOW_CACHED_PAGE));
+        cache_button->SetBoolean("defaultLabel", true);
       }
       cache_button->SetString("cacheUrl", cache_url);
       cache_button->SetInteger("trackingId", cache_tracking_id);
       error_strings->Set("cacheButton", cache_button.release());
 
       // Remove the item from suggestions dictionary so that it does not get
       // displayed by the template in the details section.
       suggestions->Remove(0, nullptr);
     }
   }
 }