[Reland] Refactor WebappRegistry into a singleton instance.

chrome/browser/android/webapps/webapp_registry.h

Index: chrome/browser/android/webapps/webapp_registry.h
diff --git a/chrome/browser/android/webapps/webapp_registry.h b/chrome/browser/android/webapps/webapp_registry.h
index 029a3dbbacb1b461385f38c66623572edab58abe..275271043115f0d10d5b7d959f4db1000edad6f2 100644
--- a/chrome/browser/android/webapps/webapp_registry.h
+++ b/chrome/browser/android/webapps/webapp_registry.h
@@ -5,8 +5,6 @@
 #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"
 
@@ -22,19 +20,14 @@ class WebappRegistry {
   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);