[sync] Isolate FOREIGN_SESSION_UPDATED notification in ProfileSyncService

chrome/browser/android/foreign_session_helper.h

 // Copyright 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.
 
 #ifndef CHROME_BROWSER_ANDROID_FOREIGN_SESSION_HELPER_H_
 #define CHROME_BROWSER_ANDROID_FOREIGN_SESSION_HELPER_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/sync_driver/sync_service_observer.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 
 using base::android::ScopedJavaLocalRef;
 
 struct SessionWindow;
 
 namespace browser_sync {
 struct SyncedSession;
 }  // namespace browser_sync
 
 namespace sync_driver {
 class SyncService;
 }  // namespace sync_driver
 
-class ForeignSessionHelper : public content::NotificationObserver,
-                             public sync_driver::SyncServiceObserver {
+class ForeignSessionHelper : public sync_driver::SyncServiceObserver {
  public:
   explicit ForeignSessionHelper(Profile* profile);
   void Destroy(JNIEnv* env, jobject obj);
   jboolean IsTabSyncEnabled(JNIEnv* env, jobject obj);
   void TriggerSessionSync(JNIEnv* env, jobject obj);
   void SetOnForeignSessionCallback(JNIEnv* env, jobject obj, jobject callback);
   jboolean GetForeignSessions(JNIEnv* env, jobject obj, jobject result);
   jboolean OpenForeignSessionTab(JNIEnv* env,
                                  jobject obj,
                                  jobject j_tab,
                                  jstring session_tag,
                                  jint tab_id,
                                  jint disposition);
   void DeleteForeignSession(JNIEnv* env, jobject obj, jstring session_tag);
 
-  // NotificationObserver implemenation
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
-
   // sync_driver::SyncServiceObserver implementation
   void OnStateChanged() override {}
   void OnSyncConfigurationCompleted() override;
+  void OnForeignSessionUpdated() override;
 
   static bool RegisterForeignSessionHelper(JNIEnv* env);
 
  private:
   ~ForeignSessionHelper() override;
 
   // Fires |callback_| if it is not null.
   void FireForeignSessionCallback();
 
   Profile* profile_;  // weak
   base::android::ScopedJavaGlobalRef<jobject> callback_;
-  content::NotificationRegistrar registrar_;
   ScopedObserver<sync_driver::SyncService, sync_driver::SyncServiceObserver>
       scoped_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ForeignSessionHelper);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_FOREIGN_SESSION_HELPER_H_