Add metrics for the number of attached displays.

chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc

 // Copyright (c) 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 "chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/cpu.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/sys_info.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/time/time.h"
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_browser_main.h"
 #include "chrome/browser/mac/bluetooth_utility.h"
 #include "chrome/browser/pref_service_flags_storage.h"
 #include "chrome/browser/shell_integration.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/base/touch/touch_device.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/events/event_switches.h"
+#include "ui/gfx/screen.h"
 
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
 #include <gnu/libc-version.h>
 
 #include "base/version.h"
 #if defined(USE_X11)
 #include "ui/base/x/x11_util.h"
 #endif
 #endif  // defined(OS_LINUX) && !defined(OS_CHROMEOS)
 
@@ skipping 177 matching lines @@
     NOTREACHED();
     return;
   }
 
   UMA_HISTOGRAM_ENUMERATION("Touchscreen.TouchEventsEnabled", state,
                             UMA_TOUCH_EVENTS_STATE_COUNT);
 }
 
 }  // namespace
 
-ChromeBrowserMainExtraPartsMetrics::ChromeBrowserMainExtraPartsMetrics() {
+ChromeBrowserMainExtraPartsMetrics::ChromeBrowserMainExtraPartsMetrics()
+    : display_count_(0), is_screen_observer_(false) {
 }
 
 ChromeBrowserMainExtraPartsMetrics::~ChromeBrowserMainExtraPartsMetrics() {
+  if (is_screen_observer_)
+    gfx::Screen::GetNativeScreen()->RemoveObserver(this);
 }
 
 void ChromeBrowserMainExtraPartsMetrics::PreProfileInit() {
   RecordMicroArchitectureStats();
 }
 
 void ChromeBrowserMainExtraPartsMetrics::PreBrowserStart() {
   about_flags::PrefServiceFlagsStorage flags_storage_(
       g_browser_process->local_state());
   about_flags::RecordUMAStatistics(&flags_storage_);
@@ skipping 10 matching lines @@
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   RecordMacMetrics();
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 
   const int kStartupMetricsGatheringDelaySeconds = 45;
   content::BrowserThread::GetBlockingPool()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&RecordStartupMetricsOnBlockingPool),
       base::TimeDelta::FromSeconds(kStartupMetricsGatheringDelaySeconds));
+
+  display_count_ = gfx::Screen::GetNativeScreen()->GetNumDisplays();
+  UMA_HISTOGRAM_COUNTS_100("Hardware.Display.Count.OnStartup", display_count_);
+  gfx::Screen::GetNativeScreen()->AddObserver(this);
+  is_screen_observer_ = true;
+}
+
+void ChromeBrowserMainExtraPartsMetrics::OnDisplayAdded(
+    const gfx::Display& new_display) {
+  EmitDisplaysChangedMetric();
+}
+
+void ChromeBrowserMainExtraPartsMetrics::OnDisplayRemoved(
+    const gfx::Display& old_display) {
+  EmitDisplaysChangedMetric();
+}
+
+void ChromeBrowserMainExtraPartsMetrics::OnDisplayMetricsChanged(
+    const gfx::Display& display,
+    uint32_t changed_metrics) {
+}
+
+void ChromeBrowserMainExtraPartsMetrics::EmitDisplaysChangedMetric() {
+  int display_count = gfx::Screen::GetNativeScreen()->GetNumDisplays();
+  if (display_count != display_count_) {
+    display_count_ = display_count;
+    UMA_HISTOGRAM_COUNTS_100("Hardware.Display.Count.OnChange", display_count_);
+  }
 }
 
 namespace chrome {
 
 void AddMetricsExtraParts(ChromeBrowserMainParts* main_parts) {
   main_parts->AddParts(new ChromeBrowserMainExtraPartsMetrics());
 }
 
 }  // namespace chrome