Start the migration of passwords from the Keychain.

chrome/browser/password_manager/password_store_mac.cc

Index: chrome/browser/password_manager/password_store_mac.cc
diff --git a/chrome/browser/password_manager/password_store_mac.cc b/chrome/browser/password_manager/password_store_mac.cc
index 32473611770d5742e22bf3fb0b0ef05659d7788a..752b54481e9d79faf3f5650d26198d0b2bfe6eec 100644
--- a/chrome/browser/password_manager/password_store_mac.cc
+++ b/chrome/browser/password_manager/password_store_mac.cc
@@ -960,7 +960,6 @@ PasswordStoreMac::~PasswordStoreMac() {}
 
 void PasswordStoreMac::InitWithTaskRunner(
     scoped_refptr<base::SingleThreadTaskRunner> background_task_runner) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

[vabr (Chromium), 2015/07/03 08:40:47]

Just out of curiosity, why is this removed?

[vasilii, 2015/07/03 12:59:10]

Because now it's called on the background thread where db_thread_runner_ is
mostly accessed.

[vabr (Chromium), 2015/07/06 09:50:19]

Acknowledged.

   db_thread_runner_ = background_task_runner;
 }
 
@@ -1050,7 +1049,8 @@ PasswordStoreMac::MigrationResult PasswordStoreMac::ImportFromKeychain() {
 void PasswordStoreMac::set_login_metadata_db(
     password_manager::LoginDatabase* login_db) {
   login_metadata_db_ = login_db;
-  login_metadata_db_->set_clear_password_values(true);
+  if (login_metadata_db_)
+    login_metadata_db_->set_clear_password_values(true);
 }
 
 bool PasswordStoreMac::Init(