Change PrefStore::ReadResult to a boolean.

base/prefs/overlay_user_pref_store.h

Index: base/prefs/overlay_user_pref_store.h
diff --git a/base/prefs/overlay_user_pref_store.h b/base/prefs/overlay_user_pref_store.h
index 0b105aaf82bd83f2a4c6e9c642be9ae7a97471a5..120d405246aad77cf64615fef9350228837b56b7 100644
--- a/base/prefs/overlay_user_pref_store.h
+++ b/base/prefs/overlay_user_pref_store.h
@@ -34,12 +34,12 @@ class BASE_PREFS_EXPORT OverlayUserPrefStore : public PersistentPrefStore,
   virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE;
   virtual size_t NumberOfObservers() const OVERRIDE;
   virtual bool IsInitializationComplete() const OVERRIDE;
-  virtual ReadResult GetValue(const std::string& key,
-                              const base::Value** result) const OVERRIDE;
+  virtual bool GetValue(const std::string& key,
+                        const base::Value** result) const OVERRIDE;
 
   // Methods of PersistentPrefStore.
-  virtual ReadResult GetMutableValue(const std::string& key,
-                                     base::Value** result) OVERRIDE;
+  virtual bool GetMutableValue(const std::string& key,
+                               base::Value** result) OVERRIDE;
   virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE;
   virtual void SetValueSilently(const std::string& key,
                                 base::Value* value) OVERRIDE;