[Reland] Refactor WebappRegistry into a singleton instance.

chrome/browser/android/webapps/webapp_registry.h

 // Copyright 2015 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_WEBAPPS_WEBAPP_REGISTRY_H_
 #define CHROME_BROWSER_ANDROID_WEBAPPS_WEBAPP_REGISTRY_H_
 
-#include "base/android/jni_android.h"
-#include "base/android/scoped_java_ref.h"
 #include "base/callback_forward.h"
 #include "base/macros.h"
 
 class GURL;
 
 // WebappRegistry is the C++ counterpart of
 // org.chromium.chrome.browser.webapp's WebappRegistry in Java.
 // All methods in this class which make JNI calls should be declared virtual and
 // mocked out in C++ unit tests. The JNI call cannot be made in this environment
 // as the Java side will not be initialised.
 class WebappRegistry {
  public:
   WebappRegistry() { }
   virtual ~WebappRegistry() { }
 
-  // Registers JNI hooks.
-  static bool RegisterWebappRegistry(JNIEnv* env);
-
   // Cleans up data stored by web apps on URLs matching |url_filter|.
   virtual void UnregisterWebappsForUrls(
-      const base::Callback<bool(const GURL&)>& url_filter,
-      const base::Closure& callback);
+      const base::Callback<bool(const GURL&)>& url_filter);
 
   // Removes history data (last used time and URLs) stored by web apps with
   // URLs matching |url_filter|, whilst leaving other data intact.
   virtual void ClearWebappHistoryForUrls(
-      const base::Callback<bool(const GURL&)>& url_filter,
-      const base::Closure& callback);
+      const base::Callback<bool(const GURL&)>& url_filter);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WebappRegistry);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_WEBAPPS_WEBAPP_REGISTRY_H_