Introduce a new way of using ScopedUserPrefUpdate that ensures notifications are sent.

This new ScopedUserPrefUpdate class should subsitute access to GetMutableList() and GetMutableDictionary() in PrefService. It ensures that update notifications are sent.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/6757011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@79821 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 30 insertions, 2 deletions

diff --git a/chrome/browser/prefs/scoped_user_pref_update.cc b/chrome/browser/prefs/scoped_user_pref_update.cc
index 3ef0029..bc033f1 100644
--- a/chrome/browser/prefs/scoped_user_pref_update.cc
+++ b/chrome/browser/prefs/scoped_user_pref_update.cc
@@ -4,11 +4,39 @@
 
 #include "chrome/browser/prefs/scoped_user_pref_update.h"
 
+#include "base/logging.h"
 #include "chrome/browser/prefs/pref_notifier.h"
 #include "chrome/browser/prefs/pref_service.h"
 
-ScopedUserPrefUpdate::ScopedUserPrefUpdate(
-    PrefService* service, const char* path)
+namespace subtle {
+
+ScopedUserPrefUpdateBase::ScopedUserPrefUpdateBase(PrefService* service,
+                                                   const char* path)
+    : service_(service),
+      path_(path),
+      value_(NULL) {}
+
+ScopedUserPrefUpdateBase::~ScopedUserPrefUpdateBase() {
+  Notify();
+}
+
+Value* ScopedUserPrefUpdateBase::Get(Value::ValueType type) {
+  if (!value_)
+    value_ = service_->GetMutableUserPref(path_.c_str(), type);
+  return value_;
+}
+
+void ScopedUserPrefUpdateBase::Notify() {
+  if (value_) {
+    service_->ReportUserPrefChanged(path_);
+    value_ = NULL;
+  }
+}
+
+}  // namespace subtle
+
+ScopedUserPrefUpdate::ScopedUserPrefUpdate(PrefService* service,
+                                           const char* path)
     : service_(service),
       path_(path) {}