Switch case fall through property for the cases that have same case content.

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 637ec70b81f1eafacccd5a691f17ec4db4481bc8..ae15cd70659cee76ae41478e0de90819c5794930 100644
--- a/base/prefs/json_pref_store.cc
+++ b/base/prefs/json_pref_store.cc
@@ -354,7 +354,6 @@ void JsonPrefStore::OnFileRead(scoped_ptr<ReadResult> read_result) {
       case PREF_READ_ERROR_NO_FILE:
         // If the file just doesn't exist, maybe this is first run.  In any case
         // there's no harm in writing out default prefs in this case.
-        break;
       case PREF_READ_ERROR_JSON_PARSE:
       case PREF_READ_ERROR_JSON_REPEAT:
         break;
@@ -362,8 +361,6 @@ void JsonPrefStore::OnFileRead(scoped_ptr<ReadResult> read_result) {
         // This is a special error code to be returned by ReadPrefs when it
         // can't complete synchronously, it should never be returned by the read
         // operation itself.
-        NOTREACHED();
-        break;
       case PREF_READ_ERROR_MAX_ENUM:
         NOTREACHED();
         break;