Remove many delegates, let's see what breaks

chrome/browser/extensions/api/notifications/extension_notification_handler.cc

 // Copyright 2017 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/extensions/api/notifications/extension_notification_handler.h"
 
+#include "base/feature_list.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/nullable_string16.h"
 #include "base/strings/string_piece.h"
 #include "chrome/browser/extensions/api/notifications/extension_notification_display_helper.h"
 #include "chrome/browser/extensions/api/notifications/extension_notification_display_helper_factory.h"
+#include "chrome/browser/notifications/notification_common.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/api/notifications.h"
+#include "chrome/common/features.h"
+#include "extensions/browser/app_window/app_window.h"
+#include "extensions/browser/app_window/app_window_registry.h"
+#include "extensions/browser/app_window/native_app_window.h"
 #include "extensions/common/constants.h"
+#include "ui/message_center/notifier_settings.h"
 #include "url/gurl.h"
 
 namespace extensions {
 
+namespace notifications = api::notifications;
+
+const base::Feature kAllowFullscreenAppNotificationsFeature{
+    "FSNotificationsApp", base::FEATURE_ENABLED_BY_DEFAULT};
+
 namespace {
 
 std::string GetExtensionId(const std::string& extension_url) {
   GURL url(extension_url);
   if (!url.is_valid() || !url.SchemeIs(extensions::kExtensionScheme))
     return "";
   return url.GetOrigin().host_piece().as_string();
 }
 
 std::unique_ptr<base::ListValue> CreateBaseEventArgs(
@@ skipping 83 matching lines @@
   EventRouter* event_router = EventRouter::Get(profile);
   if (!event_router)
     return;
 
   std::unique_ptr<Event> event(
       new Event(histogram_value, event_name, std::move(args)));
   event->user_gesture = user_gesture;
   event_router->DispatchEventToExtension(extension_id, std::move(event));
 }
 
+// Should only display when fullscreen if this app is the source of the
+// fullscreen window.
+bool ExtensionNotificationHandler::ShouldDisplayOnFullScreen(
+    Profile* profile,
+    const std::string& origin) const {
+  DCHECK(profile);
+  AppWindowRegistry::AppWindowList windows =
+      AppWindowRegistry::Get(profile)->GetAppWindowsForApp(
+          GetExtensionId(origin));
+  for (auto* window : windows) {
+    // Window must be fullscreen and visible
+    if (window->IsFullscreen() && window->GetBaseWindow()->IsActive()) {
+      bool enabled =
+          base::FeatureList::IsEnabled(kAllowFullscreenAppNotificationsFeature);
+      if (enabled) {
+        UMA_HISTOGRAM_ENUMERATION("Notifications.Display_Fullscreen.Shown",
+                                  message_center::NotifierId::APPLICATION,
+                                  message_center::NotifierId::SIZE);
+      } else {
+        UMA_HISTOGRAM_ENUMERATION("Notifications.Display_Fullscreen.Suppressed",
+                                  message_center::NotifierId::APPLICATION,
+                                  message_center::NotifierId::SIZE);
+      }
+      return enabled;
+    }
+  }
+
+  return false;
+}
+
 }  // namespace extensions