Introduce a temporary workaround to ensure tracked preferences set to empty list/dict are not confused with those that are simply not set (i.e., NULL).

Review URL: https://codereview.chromium.org/79013003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236815 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 11 insertions, 0 deletions

diff --git a/base/prefs/pref_service.cc b/base/prefs/pref_service.cc
index 296e6f2..4c707a5 100644
--- a/base/prefs/pref_service.cc
+++ b/base/prefs/pref_service.cc
@@ -297,6 +297,10 @@ const base::Value* PrefService::GetDefaultPrefValue(const char* path) const {
   return value;
 }
 
+void PrefService::MarkUserStoreNeedsEmptyValue(const std::string& key) const {
+  user_pref_store_->MarkNeedsEmptyValue(key);
+}
+
 const base::ListValue* PrefService::GetList(const char* path) const {
   DCHECK(CalledOnValidThread());
 
diff --git a/base/prefs/pref_service.h b/base/prefs/pref_service.h
index 599a2aa..9f4dc7c 100644
--- a/base/prefs/pref_service.h
+++ b/base/prefs/pref_service.h
@@ -221,6 +221,13 @@ class BASE_PREFS_EXPORT PrefService : public base::NonThreadSafe {
   // registered preference. In that case, will never return NULL.
   const base::Value* GetDefaultPrefValue(const char* path) const;
 
+  // Deprecated. Do not add calls to this method.
+  // Marks that the user store should not prune out empty values for |key| when
+  // writting to disk.
+  // TODO(gab): Enforce this at a lower level for all values and remove this
+  // method.
+  void MarkUserStoreNeedsEmptyValue(const std::string& key) const;
+
   // Returns true if a value has been set for the specified path.
   // NOTE: this is NOT the same as FindPreference. In particular
   // FindPreference returns whether RegisterXXX has been invoked, where as