Rewrite DefaultPrefStore for performance

Derive directly from PrefStore, and ignore observers
since they can't usefully observe anything. Also remove now redundant members
from ValueMapPrefStore.

BUG=158330


Review URL: https://chromiumcodereview.appspot.com/11358123

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166469 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 30 insertions, 28 deletions

diff --git a/base/prefs/default_pref_store.cc b/base/prefs/default_pref_store.cc
index c031221..eb14a50 100644
--- a/base/prefs/default_pref_store.cc
+++ b/base/prefs/default_pref_store.cc
@@ -3,19 +3,26 @@
 // found in the LICENSE file.
 
 #include "base/prefs/default_pref_store.h"
+#include "base/logging.h"
 
 using base::Value;
 
 DefaultPrefStore::DefaultPrefStore() {}
 
+PrefStore::ReadResult DefaultPrefStore::GetValue(
+    const std::string& key,
+    const base::Value** result) const {
+  return prefs_.GetValue(key, result) ? READ_OK : READ_NO_VALUE;
+}
+
 void DefaultPrefStore::SetDefaultValue(const std::string& key, Value* value) {
   CHECK(GetValue(key, NULL) == READ_NO_VALUE);
-  SetValue(key, value);
+  prefs_.SetValue(key, value);
 }
 
 void DefaultPrefStore::RemoveDefaultValue(const std::string& key) {
   CHECK(GetValue(key, NULL) == READ_OK);
-  RemoveValue(key);
+  prefs_.RemoveValue(key);
 }
 
 base::Value::Type DefaultPrefStore::GetType(const std::string& key) const {
@@ -23,4 +30,12 @@ base::Value::Type DefaultPrefStore::GetType(const std::string& key) const {
   return GetValue(key, &value) == READ_OK ? value->GetType() : Value::TYPE_NULL;
 }
 
+DefaultPrefStore::const_iterator DefaultPrefStore::begin() const {
+  return prefs_.begin();
+}
+
+DefaultPrefStore::const_iterator DefaultPrefStore::end() const {
+  return prefs_.end();
+}
+
 DefaultPrefStore::~DefaultPrefStore() {}
diff --git a/base/prefs/default_pref_store.h b/base/prefs/default_pref_store.h
index 3226cc2..e6fdbfa 100644
--- a/base/prefs/default_pref_store.h
+++ b/base/prefs/default_pref_store.h
@@ -8,15 +8,21 @@
 #include <string>
 
 #include "base/prefs/base_prefs_export.h"
-#include "base/prefs/value_map_pref_store.h"
+#include "base/prefs/pref_store.h"
+#include "base/prefs/pref_value_map.h"
 #include "base/values.h"
 
 // This PrefStore keeps track of default preference values set when a
 // preference is registered with the PrefService.
-class BASE_PREFS_EXPORT DefaultPrefStore : public ValueMapPrefStore {
+class BASE_PREFS_EXPORT DefaultPrefStore : public PrefStore {
  public:
+  typedef PrefValueMap::const_iterator const_iterator;
+
   DefaultPrefStore();
 
+  virtual ReadResult GetValue(const std::string& key,
+                              const base::Value** result) const OVERRIDE;
+
   // Stores a new |value| for |key|. Assumes ownership of |value|.
   void SetDefaultValue(const std::string& key, Value* value);
 
@@ -27,10 +33,15 @@ class BASE_PREFS_EXPORT DefaultPrefStore : public ValueMapPrefStore {
   // has not been registered.
   base::Value::Type GetType(const std::string& key) const;
 
+  const_iterator begin() const;
+  const_iterator end() const;
+
  protected:
   virtual ~DefaultPrefStore();
 
  private:
+  PrefValueMap prefs_;
+
   DISALLOW_COPY_AND_ASSIGN(DefaultPrefStore);
 };
 
diff --git a/base/prefs/value_map_pref_store.cc b/base/prefs/value_map_pref_store.cc
index dc33384..f1eb440 100644
--- a/base/prefs/value_map_pref_store.cc
+++ b/base/prefs/value_map_pref_store.cc
@@ -28,22 +28,6 @@ size_t ValueMapPrefStore::NumberOfObservers() const {
   return observers_.size();
 }
 
-ValueMapPrefStore::iterator ValueMapPrefStore::begin() {
-  return prefs_.begin();
-}
-
-ValueMapPrefStore::iterator ValueMapPrefStore::end() {
-  return prefs_.end();
-}
-
-ValueMapPrefStore::const_iterator ValueMapPrefStore::begin() const {
-  return prefs_.begin();
-}
-
-ValueMapPrefStore::const_iterator ValueMapPrefStore::end() const {
-  return prefs_.end();
-}
-
 ValueMapPrefStore::~ValueMapPrefStore() {}
 
 void ValueMapPrefStore::SetValue(const std::string& key, Value* value) {
diff --git a/base/prefs/value_map_pref_store.h b/base/prefs/value_map_pref_store.h
index b8a34ae..dc79939 100644
--- a/base/prefs/value_map_pref_store.h
+++ b/base/prefs/value_map_pref_store.h
@@ -18,9 +18,6 @@
 // storing the preference values.
 class BASE_PREFS_EXPORT ValueMapPrefStore : public PrefStore {
  public:
-  typedef std::map<std::string, base::Value*>::iterator iterator;
-  typedef std::map<std::string, base::Value*>::const_iterator const_iterator;
-
   ValueMapPrefStore();
 
   // PrefStore overrides:
@@ -30,11 +27,6 @@ class BASE_PREFS_EXPORT ValueMapPrefStore : public PrefStore {
   virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE;
   virtual size_t NumberOfObservers() const OVERRIDE;
 
-  iterator begin();
-  iterator end();
-  const_iterator begin() const;
-  const_iterator end() const;
-
  protected:
   virtual ~ValueMapPrefStore();