Make a JsonPrefStore readable while mid-interception.

chrome/browser/prefs/interceptable_pref_filter.h

Index: chrome/browser/prefs/interceptable_pref_filter.h
diff --git a/chrome/browser/prefs/interceptable_pref_filter.h b/chrome/browser/prefs/interceptable_pref_filter.h
index a1ba00df23d00a625754f7d1e900cfaefc83eee7..f426a15fcd12cffdbfa11ff6a3041003bedd4053 100644
--- a/chrome/browser/prefs/interceptable_pref_filter.h
+++ b/chrome/browser/prefs/interceptable_pref_filter.h
@@ -22,15 +22,14 @@ class InterceptablePrefFilter
   // hand back the |prefs| it was handed for early filtering. |prefs_altered|
   // indicates whether the |prefs| were actually altered by the
   // FilterOnLoadInterceptor before being handed back.
-  typedef base::Callback<void(scoped_ptr<base::DictionaryValue> prefs,
-                              bool prefs_altered)> FinalizeFilterOnLoadCallback;
+  typedef base::Callback<void(bool prefs_altered)> FinalizeFilterOnLoadCallback;
 
   // A callback to be invoked from FilterOnLoad. It takes ownership of prefs
   // and may modify them before handing them back to this
   // InterceptablePrefFilter via |finalize_filter_on_load|.
   typedef base::Callback<
       void(const FinalizeFilterOnLoadCallback& finalize_filter_on_load,
-           scoped_ptr<base::DictionaryValue> prefs)> FilterOnLoadInterceptor;
+           base::DictionaryValue* prefs)> FilterOnLoadInterceptor;
 
   InterceptablePrefFilter();
   virtual ~InterceptablePrefFilter();
@@ -38,7 +37,7 @@ class InterceptablePrefFilter
   // PrefFilter partial implementation.
   virtual void FilterOnLoad(
       const PostFilterOnLoadCallback& post_filter_on_load_callback,
-      scoped_ptr<base::DictionaryValue> pref_store_contents) OVERRIDE;
+      base::DictionaryValue* pref_store_contents) OVERRIDE;
 
   // Registers |filter_on_load_interceptor| to intercept the next FilterOnLoad
   // event. At most one FilterOnLoadInterceptor should be registered per
@@ -48,11 +47,10 @@ class InterceptablePrefFilter
 
  private:
   // Does any extra filtering required by the implementation of this
-  // InterceptablePrefFilter and hands back the |pref_store_contents| to the
-  // initial caller of FilterOnLoad.
+  // InterceptablePrefFilter and invokes the initial caller of FilterOnLoad.
   virtual void FinalizeFilterOnLoad(
       const PostFilterOnLoadCallback& post_filter_on_load_callback,
-      scoped_ptr<base::DictionaryValue> pref_store_contents,
+      base::DictionaryValue* pref_store_contents,
       bool prefs_altered) = 0;
 
   // Callback to be invoked only once (and subsequently reset) on the next