Make a JsonPrefStore readable while mid-interception.

base/prefs/json_pref_store.cc

Index: base/prefs/json_pref_store.cc
diff --git a/base/prefs/json_pref_store.cc b/base/prefs/json_pref_store.cc
index a6c236261ba5d4426f2cff61bf398b8330302a9c..3eebff1486350dc5e8ed4be721716a6dc25a474c 100644
--- a/base/prefs/json_pref_store.cc
+++ b/base/prefs/json_pref_store.cc
@@ -297,8 +297,6 @@ void JsonPrefStore::RegisterOnNextSuccessfulWriteCallback(
 void JsonPrefStore::OnFileRead(scoped_ptr<base::Value> value,
                                PersistentPrefStore::PrefReadError error,
                                bool no_dir) {
-  scoped_ptr<base::DictionaryValue> unfiltered_prefs(new base::DictionaryValue);
-
   read_error_ = error;
 
   bool initialization_successful = !no_dir;
@@ -314,8 +312,7 @@ void JsonPrefStore::OnFileRead(scoped_ptr<base::Value> value,
         break;
       case PREF_READ_ERROR_NONE:
         DCHECK(value.get());
-        unfiltered_prefs.reset(
-            static_cast<base::DictionaryValue*>(value.release()));
+        prefs_.reset(static_cast<base::DictionaryValue*>(value.release()));
         break;
       case PREF_READ_ERROR_NO_FILE:
         // If the file just doesn't exist, maybe this is first run.  In any case
@@ -346,10 +343,9 @@ void JsonPrefStore::OnFileRead(scoped_ptr<base::Value> value,
     const PrefFilter::PostFilterOnLoadCallback post_filter_on_load_callback(
         base::Bind(
             &JsonPrefStore::FinalizeFileRead, this, initialization_successful));

[gab, 2014/06/11 21:12:55]

For context for Bernhard:

this CL is okay in the sense that it won't cause issues short term. However it
forces this callback to hold a reference to the JsonPrefStore which we wanted to
get rid of.

This was discussed in lengths @
https://codereview.chromium.org/324493002/diff/40001/base/prefs/json_pref_sto...

Erik will add a TODO for now explaining this so that we can proceed with a very
important change for M37 (allowing the MACs to be in the same JsonPrefStore as
their protected values: https://codereview.chromium.org/324493002) and I will
follow-up with a change to clean this up, restoring the ownership dance of the
|prefs_| and allowing us to drop the refcounting here and on the
FileThreadDeserializer.

-    pref_filter_->FilterOnLoad(post_filter_on_load_callback,
-                               unfiltered_prefs.Pass());
+    pref_filter_->FilterOnLoad(post_filter_on_load_callback, prefs_.get());
   } else {
-    FinalizeFileRead(initialization_successful, unfiltered_prefs.Pass(), false);
+    FinalizeFileRead(initialization_successful, false);
   }
 }
 
@@ -367,7 +363,6 @@ bool JsonPrefStore::SerializeData(std::string* output) {
 }
 
 void JsonPrefStore::FinalizeFileRead(bool initialization_successful,
-                                     scoped_ptr<base::DictionaryValue> prefs,
                                      bool schedule_write) {
   filtering_in_progress_ = false;
 
@@ -378,8 +373,6 @@ void JsonPrefStore::FinalizeFileRead(bool initialization_successful,
     return;
   }
 
-  prefs_ = prefs.Pass();
-
   initialized_ = true;
 
   if (schedule_write && !read_only_)