Added the Ash.Tab.TimeBetweenSwitchToExistingTabUserActions histogram to track time between tab swit

ash/metrics/user_metrics_recorder.cc

 // Copyright 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 "ash/metrics/user_metrics_recorder.h"
 
+#include "ash/metrics/user_metrics_recorder_proxy.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shelf/shelf_delegate.h"
 #include "ash/shelf/shelf_item_types.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_model.h"
 #include "ash/shelf/shelf_view.h"
 #include "ash/shelf/shelf_widget.h"
 #include "ash/shell.h"
+#include "ash/shell_delegate.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/wm/window_state.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/user_metrics.h"
 #include "ui/aura/window.h"
 
 namespace ash {
 
 namespace {
@@ skipping 150 matching lines @@
   UMA_HISTOGRAM_COUNTS_100("Ash.Shelf.NumberOfItems",
                            pinned_item_count + unpinned_item_count);
   UMA_HISTOGRAM_COUNTS_100("Ash.Shelf.NumberOfPinnedItems", pinned_item_count);
   UMA_HISTOGRAM_COUNTS_100("Ash.Shelf.NumberOfUnpinnedItems",
                            unpinned_item_count);
 }
 
 }  // namespace
 
 UserMetricsRecorder::UserMetricsRecorder() {
-  StartTimer();
+  Init(true);
 }
 
 UserMetricsRecorder::UserMetricsRecorder(bool record_periodic_metrics) {
+  Init(record_periodic_metrics);
+}
+
+void UserMetricsRecorder::Init(bool record_periodic_metrics) {
+  user_metrics_recorder_proxy_.reset(
+      ash::Shell::GetInstance()->delegate()->CreateUserMetricsRecorderProxy());
   if (record_periodic_metrics)
     StartTimer();
 }
 
 UserMetricsRecorder::~UserMetricsRecorder() {
   timer_.Stop();
 }
 
 void UserMetricsRecorder::RecordUserMetricsAction(UserMetricsAction action) {
   switch (action) {
@@ skipping 432 matching lines @@
   return IsUserActive() && !IsKioskModeActive();
 }
 
 void UserMetricsRecorder::StartTimer() {
   timer_.Start(FROM_HERE,
                base::TimeDelta::FromSeconds(kAshPeriodicMetricsTimeInSeconds),
                this, &UserMetricsRecorder::RecordPeriodicMetrics);
 }
 
 }  // namespace ash