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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_PREFS_INTERCEPTABLE_PREF_FILTER_H_
      6 #define CHROME_BROWSER_PREFS_INTERCEPTABLE_PREF_FILTER_H_
      7 
      8 #include "base/callback.h"
      9 #include "base/memory/weak_ptr.h"
     10 #include "base/prefs/pref_filter.h"
     11 #include "base/values.h"
     12 
     13 // A partial implementation of a PrefFilter whose FilterOnLoad call may be
     14 // intercepted by a FilterOnLoadInterceptor. Implementations of
     15 // InterceptablePrefFilter are expected to override FinalizeFilterOnLoad rather
     16 // than re-overriding FilterOnLoad.
     17 class InterceptablePrefFilter
     18     : public PrefFilter,
     19       public base::SupportsWeakPtr<InterceptablePrefFilter> {
     20  public:
     21   // A callback to be invoked by a FilterOnLoadInterceptor when its ready to
     22   // hand back the |prefs| it was handed for early filtering. |prefs_altered|
     23   // indicates whether the |prefs| were actually altered by the
     24   // FilterOnLoadInterceptor before being handed back.
     25   typedef base::Callback<void(scoped_ptr<base::DictionaryValue> prefs,
     26                               bool prefs_altered)> FinalizeFilterOnLoadCallback;
     27 
     28   // A callback to be invoked from FilterOnLoad. It takes ownership of prefs
     29   // and may modify them before handing them back to this
     30   // InterceptablePrefFilter via |finalize_filter_on_load|.
     31   typedef base::Callback<
     32       void(const FinalizeFilterOnLoadCallback& finalize_filter_on_load,
     33            scoped_ptr<base::DictionaryValue> prefs)> FilterOnLoadInterceptor;
     34 
     35   InterceptablePrefFilter();
     36   virtual ~InterceptablePrefFilter();
     37 
     38   // PrefFilter partial implementation.
     39   virtual void FilterOnLoad(
     40       const PostFilterOnLoadCallback& post_filter_on_load_callback,
     41       scoped_ptr<base::DictionaryValue> pref_store_contents) OVERRIDE;
     42 
     43   // Registers |filter_on_load_interceptor| to intercept the next FilterOnLoad
     44   // event. At most one FilterOnLoadInterceptor should be registered per
     45   // PrefFilter.
     46   void InterceptNextFilterOnLoad(
     47       const FilterOnLoadInterceptor& filter_on_load_interceptor);
     48 
     49  private:
     50   // Does any extra filtering required by the implementation of this
     51   // InterceptablePrefFilter and hands back the |pref_store_contents| to the
     52   // initial caller of FilterOnLoad.
     53   virtual void FinalizeFilterOnLoad(
     54       const PostFilterOnLoadCallback& post_filter_on_load_callback,
     55       scoped_ptr<base::DictionaryValue> pref_store_contents,
     56       bool prefs_altered) = 0;
     57 
     58   // Callback to be invoked only once (and subsequently reset) on the next
     59   // FilterOnLoad event. It will be allowed to modify the |prefs| handed to
     60   // FilterOnLoad before handing them back to this PrefHashFilter.
     61   FilterOnLoadInterceptor filter_on_load_interceptor_;
     62 };
     63 
     64 #endif  // CHROME_BROWSER_PREFS_INTERCEPTABLE_PREF_FILTER_H_
     65