Cache the ranges_ vector and share the ranges_ vector

chrome/browser/metrics/metrics_service.cc

 // Copyright (c) 2011 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.
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
 //
 // A MetricsService instance is typically created at application startup.  It
@@ skipping 883 matching lines @@
   // like to record: the histogram of memory usage, so we spawn a task to
   // collect the memory details and when that task is finished, it will call
   // OnMemoryDetailCollectionDone, which will call HistogramSynchronization to
   // collect histograms from all renderers and then we will call
   // OnHistogramSynchronizationDone to continue processing.
 
   // Create a callback_task for OnHistogramSynchronizationDone.
   Task* callback_task = log_sender_factory_.NewRunnableMethod(
       &MetricsService::OnHistogramSynchronizationDone);
 
+  base::StatisticsRecorder::CollectHistogramStats("Browser");
+
   // Set up the callback to task to call after we receive histograms from all
   // renderer processes. Wait time specifies how long to wait before absolutely
   // calling us back on the task.
   HistogramSynchronizer::FetchRendererHistogramsAsynchronously(
       MessageLoop::current(), callback_task,
       kMaxHistogramGatheringWaitDuration);
 }
 
 void MetricsService::OnHistogramSynchronizationDone() {
   DCHECK(IsSingleThreaded());
@@ skipping 628 matching lines @@
   if (local_state) {
     const PrefService::Preference* uma_pref =
         local_state->FindPreference(prefs::kMetricsReportingEnabled);
     if (uma_pref) {
       bool success = uma_pref->GetValue()->GetAsBoolean(&result);
       DCHECK(success);
     }
   }
   return result;
 }