Linux native notifications: Add server capabilities metrics

chrome/browser/notifications/native_notification_display_service.cc

 // Copyright 2016 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/notifications/native_notification_display_service.h"
 
+#include <utility>
+
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/nullable_string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/notifications/message_center_display_service.h"
 #include "chrome/browser/notifications/non_persistent_notification_handler.h"
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/notifications/notification_delegate.h"
 #include "chrome/browser/notifications/notification_handler.h"
 #include "chrome/browser/notifications/notification_platform_bridge.h"
 #include "chrome/browser/notifications/persistent_notification_handler.h"
@@ skipping 40 matching lines @@
 #if BUILDFLAG(ENABLE_EXTENSIONS)
   AddNotificationHandler(NotificationCommon::EXTENSION,
                          base::MakeUnique<ExtensionNotificationHandler>());
 #endif
 }
 
 NativeNotificationDisplayService::~NativeNotificationDisplayService() = default;
 
 void NativeNotificationDisplayService::OnNotificationPlatformBridgeReady(
     bool success) {
+  // If NotificationPlatformBridge initialization succeeded, use
+  // native notifications, otherwise fallback to using the Chrome
+  // message center.

[Peter Beverloo, 2017/05/03 22:52:48]

nit: I don't think this comment adds a lot, the code is clear.

[Tom (Use chromium acct), 2017/05/04 00:07:38]

Done.

+  UMA_HISTOGRAM_BOOLEAN("Notifications.UsingNativeNotificationCenter", success);
   if (success) {
     notification_bridge_ready_ = true;
   } else {
     message_center_display_service_ =
         base::MakeUnique<MessageCenterDisplayService>(
             profile_, g_browser_process->notification_ui_manager());
   }
 
   while (!actions_.empty()) {
     std::move(actions_.front()).Run();
@@ skipping 92 matching lines @@
   notification_handlers_.erase(notification_type);
 }
 
 NotificationHandler* NativeNotificationDisplayService::GetNotificationHandler(
     NotificationCommon::Type notification_type) {
   DCHECK(notification_handlers_.find(notification_type) !=
          notification_handlers_.end())
       << notification_type << " is not registered.";
   return notification_handlers_[notification_type].get();
 }