Revert 269415 "Introduce a new framework for back-and-forth trac..."

trunk/src/chrome/browser/prefs/pref_hash_filter.cc

Index: trunk/src/chrome/browser/prefs/pref_hash_filter.cc
===================================================================
--- trunk/src/chrome/browser/prefs/pref_hash_filter.cc	(revision 269437)
+++ trunk/src/chrome/browser/prefs/pref_hash_filter.cc	(working copy)
@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/prefs/persistent_pref_store.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/pref_store.h"
 #include "base/strings/string_number_conversions.h"
@@ -91,6 +92,51 @@
   user_prefs->ClearPref(prefs::kPreferenceResetTime);
 }
 
+void PrefHashFilter::MigrateValues(PersistentPrefStore* source,
+                                   PersistentPrefStore* destination) {
+  bool commit_source = false;
+  bool commit_destination = false;
+
+  scoped_ptr<PrefHashStoreTransaction> transaction =
+      pref_hash_store_->BeginTransaction();
+  for (TrackedPreferencesMap::const_iterator it = tracked_paths_.begin();
+       it != tracked_paths_.end();
+       ++it) {
+    const base::Value* source_value = NULL;
+    if (source->GetValue(it->first, &source_value)) {
+      if (!destination->GetValue(it->first, NULL)) {
+        base::DictionaryValue temp_dictionary;
+        // Copy the value from |source| into a suitable place for a
+        // TrackedPreference to act on it.
+        temp_dictionary.Set(it->first, source_value->DeepCopy());
+        // Check whether the value is correct according to our MAC. May remove
+        // the value from |temp_dictionary|.
+        it->second->EnforceAndReport(&temp_dictionary, transaction.get());
+        // Now take the value as it appears in |temp_dictionary| and put it in
+        // |destination|.
+        scoped_ptr<base::Value> checked_value;
+        if (temp_dictionary.Remove(it->first, &checked_value)) {
+          destination->SetValue(it->first, checked_value.release());
+          commit_destination = true;
+        }
+      }
+      source->RemoveValue(it->first);
+      commit_source = true;
+    }
+  }
+
+  // Order these such that a crash at any point is still recoverable. We assume
+  // that they are configured such that the writes will occur on worker threads
+  // in the order that we asked for them.
+  if (commit_destination)
+    destination->CommitPendingWrite();
+  transaction.reset();
+  // If we crash here, we will just delete the values from |source| in a future
+  // invocation of MigrateValues.
+  if (commit_source)
+    source->CommitPendingWrite();
+}
+
 void PrefHashFilter::Initialize(const PrefStore& pref_store) {
   scoped_ptr<PrefHashStoreTransaction> hash_store_transaction(
       pref_hash_store_->BeginTransaction());
@@ -104,6 +150,40 @@
   }
 }
 
+// Validates loaded preference values according to stored hashes, reports
+// validation results via UMA, and updates hashes in case of mismatch.
+bool PrefHashFilter::FilterOnLoad(base::DictionaryValue* pref_store_contents) {
+  DCHECK(pref_store_contents);
+  base::TimeTicks checkpoint = base::TimeTicks::Now();
+
+  bool did_reset = false;
+  {
+    scoped_ptr<PrefHashStoreTransaction> hash_store_transaction(
+        pref_hash_store_->BeginTransaction());
+    for (TrackedPreferencesMap::const_iterator it = tracked_paths_.begin();
+         it != tracked_paths_.end(); ++it) {
+      if (it->second->EnforceAndReport(pref_store_contents,
+                                       hash_store_transaction.get())) {
+        did_reset = true;
+      }
+    }
+  }
+
+  if (did_reset) {
+    pref_store_contents->Set(prefs::kPreferenceResetTime,
+                             new base::StringValue(base::Int64ToString(
+                                 base::Time::Now().ToInternalValue())));
+  }
+
+  // TODO(gab): Remove this histogram by Feb 21 2014; after sufficient timing
+  // data has been gathered from the wild to be confident this doesn't
+  // significantly affect startup.
+  UMA_HISTOGRAM_TIMES("Settings.FilterOnLoadTime",
+                      base::TimeTicks::Now() - checkpoint);
+
+  return did_reset;
+}
+
 // Marks |path| has having changed if it is part of |tracked_paths_|. A new hash
 // will be stored for it the next time FilterSerializeData() is invoked.
 void PrefHashFilter::FilterUpdate(const std::string& path) {
@@ -154,39 +234,3 @@
   // necessary anyways).
   pref_hash_store_->CommitPendingWrite();
 }
-
-void PrefHashFilter::FinalizeFilterOnLoad(
-    const PostFilterOnLoadCallback& post_filter_on_load_callback,
-    scoped_ptr<base::DictionaryValue> pref_store_contents,
-    bool prefs_altered) {
-  DCHECK(pref_store_contents);
-  base::TimeTicks checkpoint = base::TimeTicks::Now();
-
-  bool did_reset = false;
-  {
-    scoped_ptr<PrefHashStoreTransaction> hash_store_transaction(
-        pref_hash_store_->BeginTransaction());
-    for (TrackedPreferencesMap::const_iterator it = tracked_paths_.begin();
-         it != tracked_paths_.end(); ++it) {
-      if (it->second->EnforceAndReport(pref_store_contents.get(),
-                                       hash_store_transaction.get())) {
-        did_reset = true;
-        prefs_altered = true;
-      }
-    }
-  }
-
-  if (did_reset) {
-    pref_store_contents->Set(prefs::kPreferenceResetTime,
-                             new base::StringValue(base::Int64ToString(
-                                 base::Time::Now().ToInternalValue())));
-  }
-
-  // TODO(gab): Remove this histogram by Feb 21 2014; after sufficient timing
-  // data has been gathered from the wild to be confident this doesn't
-  // significantly affect startup.
-  UMA_HISTOGRAM_TIMES("Settings.FilterOnLoadTime",
-                      base::TimeTicks::Now() - checkpoint);
-
-  post_filter_on_load_callback.Run(pref_store_contents.Pass(), prefs_altered);
-}