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 951 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 711 matching lines @@
     thread_id = base::PlatformThread::CurrentId();
   return base::PlatformThread::CurrentId() == thread_id;
 }
 
 #if defined(OS_CHROMEOS)
 void MetricsService::StartExternalMetrics() {
   external_metrics_ = new chromeos::ExternalMetrics;
   external_metrics_->Start();
 }
 #endif