Domain Reliability: Histogram upload collector index

components/domain_reliability/context.cc

 // Copyright 2014 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 "components/domain_reliability/context.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
@@ skipping 216 matching lines @@
 
   size_t collector_index = scheduler_.OnUploadStart();
 
   uploader_->UploadReport(
       report_json,
       config_->collectors[collector_index]->upload_url,
       base::Bind(
           &DomainReliabilityContext::OnUploadComplete,
           weak_factory_.GetWeakPtr()));
 
-  UMA_HISTOGRAM_BOOLEAN("DomainReliability.UploadFailover",
-                        collector_index > 0);
+  UMA_HISTOGRAM_SPARSE_SLOWLY("DomainReliability.UploadCollectorIndex",
+                              static_cast<int>(collector_index));
   if (!last_upload_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("DomainReliability.UploadInterval",
                              upload_time_ - last_upload_time_);
   }
 }
 
 void DomainReliabilityContext::OnUploadComplete(bool success) {
   if (success)
     CommitUpload();
   else
@@ skipping 64 matching lines @@
 
   beacons_.pop_front();
 
   // If that just removed a beacon counted in uploading_beacons_size_, decrement
   // that.
   if (uploading_beacons_size_ > 0)
     --uploading_beacons_size_;
 }
 
 }  // namespace domain_reliability