cros: Prevent shut down on lid-close during migration.

chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
index e47c7ad10f96d3a801b44b0f14e9630dd8d51b20..5f97b4bb25a47248dba8d12df33665b986faa20f 100644
--- a/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
@@ -27,6 +27,7 @@
 #include "chromeos/cryptohome/homedir_methods.h"
 #include "chromeos/dbus/cryptohome_client.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/dbus/power_manager/policy.pb.h"
 #include "chromeos/dbus/power_manager/power_supply_properties.pb.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "components/login/localized_values_builder.h"
@@ -351,6 +352,17 @@ void EncryptionMigrationScreenHandler::OnMountExistingVault(
     return;
   }
 
+  // Prevent shut down on lid close.
+  // We set SUSPEND instead of DO_NOTHING to avoid potential heat issue.
+  // Note that, once migration finishes, the system will shut down or restart
+  // regardless of the migration result (success or failures). Given this, we
+  // don't need to restore the power policy.
+  power_manager::PowerManagementPolicy policy;
+  policy.set_lid_closed_action(
+      power_manager::PowerManagementPolicy_Action_SUSPEND);
+  DBusThreadManager::Get()->GetPowerManagerClient()->SetPolicy(policy);

[Daniel Erat, 2017/05/26 13:45:34]

you can't send a policy directly like this; it'll be overwritten as soon as we
decide to send another policy.

i tried to explain earlier that you should add a new method to
PowerPolicyController so that it will continue to be the only thing sending
policies. i think that something like this will work:

1. add PowerPolicyController::SetEncryptionMigrationActive(bool active)
2. make it update a encryption_migration_active_ bool member and call
SendCurrentPolicy()
3. after the chrome_is_exiting_ code near the end of that method, add something
like this:

if (encryption_migration_active_ &&
    policy.lid_closed_action() != ..._Action_DO_NOTHING) {
  policy.set_lid_closed_action(..._Action_SUSPEND);
  causes += (causes.empty() ? "" : ", ") + "encryption migration";
}

+
+  // Start migration with a progress listener.
   DBusThreadManager::Get()
       ->GetCryptohomeClient()
       ->SetDircryptoMigrationProgressHandler(