Battery Status API: add UMA logging for Windows.

content/browser/battery_status/battery_status_manager_win.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 "content/browser/battery_status/battery_status_manager_win.h"
 
 #include "base/memory/ref_counted.h"
+#include "base/metrics/histogram.h"
 #include "base/strings/string16.h"
 #include "base/win/message_window.h"
 #include "base/win/windows_version.h"
 #include "content/browser/battery_status/battery_status_manager.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace content {
 
 namespace {
 
 typedef BatteryStatusService::BatteryUpdateCallback BatteryCallback;
 
 const wchar_t kWindowClassName[] = L"BatteryStatusMessageWindow";
 
+// This enum is used for histogram. Don't change the order of the existing
+// values.
+enum NumberBatteriesType {
+  NO_BATTERY = 0,
+  ONE_OR_MORE_BATTERIES = 1,
+  UNKNOWN_BATTERIES = 2,
+  BATTERY_TYPES_COUNT = 3,
+};
+
+void UpdateNumberBatteriesHistogram(NumberBatteriesType count) {
+  UMA_HISTOGRAM_ENUMERATION("BatteryStatus.NumberBatteriesWin",
+                            count,
+                            BATTERY_TYPES_COUNT);
+}
+
+void UpdateNumberBatteriesHistogram() {
+  SYSTEM_POWER_STATUS win_status;
+  if (!GetSystemPowerStatus(&win_status)) {
+    UpdateNumberBatteriesHistogram(UNKNOWN_BATTERIES);
+    return;
+  }
+
+  if (win_status.BatteryFlag == 255)
+    UpdateNumberBatteriesHistogram(UNKNOWN_BATTERIES);
+  else if (win_status.BatteryFlag == 128)
+    UpdateNumberBatteriesHistogram(NO_BATTERY);
+  else
+    UpdateNumberBatteriesHistogram(ONE_OR_MORE_BATTERIES);
+}
+
 // Message-only window for handling battery changes on Windows.
 class BatteryStatusObserver
     : public base::RefCountedThreadSafe<BatteryStatusObserver> {
  public:
   explicit BatteryStatusObserver(const BatteryCallback& callback)
       : power_handle_(NULL),
         battery_change_handle_(NULL),
         callback_(callback) {
   }
 
@@ skipping 29 matching lines @@
       // versions prior to Vista, see crbug.com/402466.
       power_handle_ =
           RegisterNotification(&GUID_ACDC_POWER_SOURCE);
       battery_change_handle_ =
           RegisterNotification(&GUID_BATTERY_PERCENTAGE_REMAINING);
     } else {
       // Could not create a message window, execute callback with the default
       // values.
       callback_.Run(blink::WebBatteryStatus());
     }
+
+    UpdateNumberBatteriesHistogram();
   }
 
   void StopOnUI() {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     if (!window_)
       return;
 
     if (power_handle_)
       UnregisterNotification(power_handle_);
     if (battery_change_handle_)
@@ skipping 116 matching lines @@
 }
 
 // static
 scoped_ptr<BatteryStatusManager> BatteryStatusManager::Create(
     const BatteryStatusService::BatteryUpdateCallback& callback) {
   return scoped_ptr<BatteryStatusManager>(
       new BatteryStatusManagerWin(callback));
 }
 
 }  // namespace content