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

chromeos/dbus/session_manager_client.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROMEOS_DBUS_SESSION_MANAGER_CLIENT_H_
 #define CHROMEOS_DBUS_SESSION_MANAGER_CLIENT_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 214 matching lines @@
   // failed to start an instance or session manager can not be reached).
   virtual void StartArcInstance(const cryptohome::Identification& cryptohome_id,
                                 const ArcCallback& callback) = 0;
 
   // Asynchronously stops the ARC instance.  Upon completion, invokes
   // |callback| with the result; true on success, false on failure (either
   // session manager failed to stop an instance or session manager can not be
   // reached).
   virtual void StopArcInstance(const ArcCallback& callback) = 0;
 
+  // Prioritizes the ARC instance by removing cgroups restrictions that
+  // session_manager applies to the instance by default. Upon completion,
+  // invokes |callback| with the result; true on success, false on failure.
+  // Calling this multiple times is okay. Such calls except the first one
+  // will be ignored.
+  virtual void PrioritizeArcInstance(const ArcCallback& callback) = 0;
+
   // Asynchronously retrieves the timestamp which ARC instance is invoked or
   // returns false if there is no ARC instance or ARC is not available.
   virtual void GetArcStartTime(const GetArcStartTimeCallback& callback) = 0;
 
   // Asynchronously removes all ARC user data for the user whose cryptohome is
   // located by |cryptohome_id|. Upon completion, invokes |callback| with the
   // result; true on success, false on failure (either session manager failed
   // to remove user data or session manager can not be reached).
   virtual void RemoveArcData(const cryptohome::Identification& cryptohome_id,
                              const ArcCallback& callback) = 0;
 
   // Creates the instance.
   static SessionManagerClient* Create(DBusClientImplementationType type);
 
   ~SessionManagerClient() override;
 
  protected:
   // Create() should be used instead.
   SessionManagerClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SessionManagerClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_SESSION_MANAGER_CLIENT_H_