Speed up ARC boot if the user launches ARC app while ARC is not ready

chromeos/dbus/fake_session_manager_client.cc

Index: chromeos/dbus/fake_session_manager_client.cc
diff --git a/chromeos/dbus/fake_session_manager_client.cc b/chromeos/dbus/fake_session_manager_client.cc
index 0f41c79728b520622d022cbede848eda7b8818c0..52ee33b06c80c2ee5a8836958cdff010e2549021 100644
--- a/chromeos/dbus/fake_session_manager_client.cc
+++ b/chromeos/dbus/fake_session_manager_client.cc
@@ -171,6 +171,12 @@ void FakeSessionManagerClient::StopArcInstance(const ArcCallback& callback) {
       FROM_HERE, base::Bind(callback, arc_available_));
 }
 
+void FakeSessionManagerClient::PrioritizeArcInstance(
+    const ArcCallback& callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, arc_available_));
+}
+
 void FakeSessionManagerClient::GetArcStartTime(
     const GetArcStartTimeCallback& callback) {
   base::ThreadTaskRunnerHandle::Get()->PostTask(