Change PrefStore::ReadResult to a boolean.

base/prefs/value_map_pref_store.h

Index: base/prefs/value_map_pref_store.h
diff --git a/base/prefs/value_map_pref_store.h b/base/prefs/value_map_pref_store.h
index dc7993978c1074c0d33cff3aa2eee8201059cb42..c9c9b1c905522a6f5cd3c34fd984dd0cadd754b8 100644
--- a/base/prefs/value_map_pref_store.h
+++ b/base/prefs/value_map_pref_store.h
@@ -21,8 +21,8 @@ class BASE_PREFS_EXPORT ValueMapPrefStore : public PrefStore {
   ValueMapPrefStore();
 
   // PrefStore overrides:
-  virtual ReadResult GetValue(const std::string& key,
-                              const base::Value** value) const OVERRIDE;
+  virtual bool GetValue(const std::string& key,
+                        const base::Value** value) const OVERRIDE;
   virtual void AddObserver(PrefStore::Observer* observer) OVERRIDE;
   virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE;
   virtual size_t NumberOfObservers() const OVERRIDE;