Make Android notifications rely on the native notification flag

chrome/browser/notifications/notification_display_service_factory.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/notification_display_service_factory.h"
 
 #include "base/command_line.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/notifications/message_center_display_service.h"
@@ skipping 21 matching lines @@
   return base::Singleton<NotificationDisplayServiceFactory>::get();
 }
 
 NotificationDisplayServiceFactory::NotificationDisplayServiceFactory()
     : BrowserContextKeyedServiceFactory(
           "NotificationDisplayService",
           BrowserContextDependencyManager::GetInstance()) {}
 
 // Selection of the implementation works as follows:
 //   - Android always uses the NativeNotificationDisplayService.
-//   - Mac uses the MessageCenterDisplayService by default, but can use the
-//     NativeNotificationDisplayService by using the chrome://flags or via
-//     the --enable-features=NativeNotifications command line flag.
+//   - Mac uses the NativeNotificationDisplayService by default but
+//     can revert to MessageCenterDisplayService via
+//     chrome://flags#enable-native-notifications or Finch
+//   - Linux uses MessageCenterDisplayService by default but can switch
+//     to NativeNotificationDisplayService via
+//     chrome://flags#enable-native-notifications
 //   - All other platforms always use the MessageCenterDisplayService.
 KeyedService* NotificationDisplayServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
 #if BUILDFLAG(ENABLE_NATIVE_NOTIFICATIONS)
-#if defined(OS_ANDROID)
-  return new NativeNotificationDisplayService(
-      Profile::FromBrowserContext(context),
-      g_browser_process->notification_platform_bridge());
-#else   // defined(OS_ANDROID)
+  // Note that for android this flag must always be true.

[Peter Beverloo, 2017/04/25 16:31:29]

DCHECK?

[Miguel Garcia, 2017/05/03 07:11:33]

As discussed offline in addition to the DCHECK I added some code to protect us
against someone accidentally disabling the flag in finch and crash all android
browsers as a result.

   if (base::FeatureList::IsEnabled(features::kNativeNotifications) &&
       g_browser_process->notification_platform_bridge()) {
     return new NativeNotificationDisplayService(
         Profile::FromBrowserContext(context),
         g_browser_process->notification_platform_bridge());
   }
-#endif  // defined(OS_ANDROID)
 #endif  // BUILDFLAG(ENABLE_NATIVE_NOTIFICATIONS)
   return new MessageCenterDisplayService(
       Profile::FromBrowserContext(context),
       g_browser_process->notification_ui_manager());
 }
 
 content::BrowserContext*
 NotificationDisplayServiceFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return chrome::GetBrowserContextOwnInstanceInIncognito(context);
 }