Start the migration of passwords from the Keychain.

chrome/browser/password_manager/password_store_proxy_mac.cc

Index: chrome/browser/password_manager/password_store_proxy_mac.cc
diff --git a/chrome/browser/password_manager/password_store_proxy_mac.cc b/chrome/browser/password_manager/password_store_proxy_mac.cc
index 2d16b7ecfef43b1104d789ce34c678d0ad4f26a1..3ed1a3f6e948ebedeaaba58f6f70666b3e5dc56b 100644
--- a/chrome/browser/password_manager/password_store_proxy_mac.cc
+++ b/chrome/browser/password_manager/password_store_proxy_mac.cc
@@ -4,23 +4,34 @@
 
 #include "chrome/browser/password_manager/password_store_proxy_mac.h"
 
+#include "base/metrics/histogram_macros.h"
 #include "chrome/browser/password_manager/password_store_mac.h"
 #include "chrome/browser/password_manager/simple_password_store_mac.h"
 #include "content/public/browser/browser_thread.h"
 #include "crypto/apple_keychain.h"
 
+using password_manager::MigrationStatus;
 using password_manager::PasswordStoreChangeList;
 
 PasswordStoreProxyMac::PasswordStoreProxyMac(
     scoped_refptr<base::SingleThreadTaskRunner> main_thread_runner,
     scoped_ptr<crypto::AppleKeychain> keychain,
-    scoped_ptr<password_manager::LoginDatabase> login_db)
+    scoped_ptr<password_manager::LoginDatabase> login_db,
+    PrefService* prefs)
     : PasswordStore(main_thread_runner, nullptr),
       login_metadata_db_(login_db.Pass()) {
   DCHECK(login_metadata_db_);
-  // TODO(vasilii): for now the class is just a wrapper around PasswordStoreMac.
-  password_store_mac_ =
-      new PasswordStoreMac(main_thread_runner, nullptr, keychain.Pass());
+  migration_status_.Init(password_manager::prefs::kKeychainMigrationStatus,
+                         prefs);
+  if (migration_status_.GetValue() ==
+      static_cast<int>(MigrationStatus::MIGRATED)) {
+    // The login database will be set later after initialization.
+    password_store_simple_ =
+        new SimplePasswordStoreMac(main_thread_runner, nullptr, nullptr);
+  } else {
+    password_store_mac_ =
+        new PasswordStoreMac(main_thread_runner, nullptr, keychain.Pass());
+  }
 }
 
 PasswordStoreProxyMac::~PasswordStoreProxyMac() {
@@ -37,17 +48,30 @@ bool PasswordStoreProxyMac::Init(
     return false;
   }
 
-  ScheduleTask(
-      base::Bind(&PasswordStoreProxyMac::InitOnBackgroundThread, this));
-  password_store_mac_->InitWithTaskRunner(GetBackgroundTaskRunner());
-  return password_manager::PasswordStore::Init(flare);
+  if (!password_manager::PasswordStore::Init(flare))
+    return false;
+
+  return ScheduleTask(
+      base::Bind(&PasswordStoreProxyMac::InitOnBackgroundThread, this,
+                 static_cast<MigrationStatus>(migration_status_.GetValue())));
 }
 
 void PasswordStoreProxyMac::Shutdown() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   PasswordStore::Shutdown();
-  GetBackend()->Shutdown();
   thread_->Stop();
+
+  // Execute the task which are still pending.
+  FlushPendingTasks();
+
+  // Unsubscribe the observer, otherwise it's too late in the destructor.
+  migration_status_.Destroy();
+
+  // After the thread has stopped it's impossible to switch from one backend to
+  // another. GetBackend() returns the correct result.
+  // The backend doesn't need the background thread as PasswordStore::Init() and
+  // other public methods were never called on it.
+  GetBackend()->Shutdown();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
@@ -61,15 +85,63 @@ password_manager::PasswordStore* PasswordStoreProxyMac::GetBackend() const {
   return password_store_simple_.get();
 }
 
-void PasswordStoreProxyMac::InitOnBackgroundThread() {
+void PasswordStoreProxyMac::InitOnBackgroundThread(MigrationStatus status) {
   DCHECK(GetBackgroundTaskRunner()->BelongsToCurrentThread());
   if (!login_metadata_db_->Init()) {
     login_metadata_db_.reset();
     LOG(ERROR) << "Could not create/open login database.";
-    return;
   }
-  if (password_store_mac_)
+
+  if (status == MigrationStatus::MIGRATED) {
+    password_store_simple_->InitWithTaskRunner(GetBackgroundTaskRunner(),
+                                               login_metadata_db_.Pass());
+  } else {
     password_store_mac_->set_login_metadata_db(login_metadata_db_.get());
+    password_store_mac_->InitWithTaskRunner(GetBackgroundTaskRunner());
+    if (login_metadata_db_ && (status == MigrationStatus::NOT_STARTED ||
+                               status == MigrationStatus::FAILED_ONCE)) {
+      // Let's try to migrate the passwords.
+      if (password_store_mac_->ImportFromKeychain() ==
+          PasswordStoreMac::MIGRATION_OK) {
+        status = MigrationStatus::MIGRATED;
+        // Switch from |password_store_mac_| to |password_store_simple_|.
+        password_store_mac_->set_login_metadata_db(nullptr);
+        pending_ui_tasks_.push_back(
+            base::Bind(&PasswordStoreMac::Shutdown, password_store_mac_));
+        password_store_mac_ = nullptr;
+        DCHECK(!password_store_simple_);
+        password_store_simple_ = new SimplePasswordStoreMac(
+            main_thread_runner_, GetBackgroundTaskRunner(),
+            login_metadata_db_.Pass());
+      } else {
+        status = (status == MigrationStatus::FAILED_ONCE
+                      ? MigrationStatus::FAILED_TWICE
+                      : MigrationStatus::FAILED_ONCE);
+      }
+      pending_ui_tasks_.push_back(
+          base::Bind(&PasswordStoreProxyMac::UpdateStatusPref, this, status));
+    }
+  }
+  if (!pending_ui_tasks_.empty()) {
+    main_thread_runner_->PostTask(
+        FROM_HERE, base::Bind(&PasswordStoreProxyMac::FlushPendingTasks, this));
+  }
+  UMA_HISTOGRAM_ENUMERATION(
+      "PasswordManager.KeychainMigration.Status", static_cast<int>(status),
+      static_cast<int>(MigrationStatus::MIGRATION_STATUS_COUNT));
+  DCHECK(GetBackend());
+}
+
+void PasswordStoreProxyMac::UpdateStatusPref(MigrationStatus status) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  migration_status_.SetValue(static_cast<int>(status));
+}
+
+void PasswordStoreProxyMac::FlushPendingTasks() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  for (auto& task : pending_ui_tasks_)
+    task.Run();
+  pending_ui_tasks_.clear();
 }
 
 void PasswordStoreProxyMac::ReportMetricsImpl(