Additions to Activities to allow resource management

athena/activity/public/activity.h

 // Copyright 2014 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 ATHENA_ACTIVITY_PUBLIC_ACTIVITY_H_
 #define ATHENA_ACTIVITY_PUBLIC_ACTIVITY_H_
 
 #include <string>
 
 #include "athena/athena_export.h"
 
 namespace athena {
 
 class ActivityViewModel;
 
+// This class is a high level abstraction of an activity (which could be either
+// a web page or a V1/V2 app/extension). Through this class the activity can
+// be controlled (e.g. loaded / unloaded).
+// An Activity gets created with state |ACTIVITY_UNLOADED|.
+// Requesting |ACTIVITY_VISIBLE| or |ACTIVITY_INVISIBLE| will load it.
+// Once an activity was |ACTIVITY_INVISIBLE| for a while it can be transitioned
+// into |ACTIVITY_BACKGROUND_LOW_PRIORITY| to surrender more resources. After
+// more time it can be transitions to |ACTIVITY_PERSISTENT| in which it only
+// has it's runtime state left. At any time it can be transitioned back to one
+// of the higher levels or unloaded via |ACTIVITY_UNLOADED|.
+// Note that the resource manager will also query the media state before
+// deciding if an activity can put into a lower state then |ACTIVITY_INVISIBLE|.
 class ATHENA_EXPORT Activity {
  public:
+  // The state of an activity which could either be set or requested by e.g. the
+  // resource management system.
+  enum ActivityState {
+    // The activity is allowed to have gpu compositor layers and can be visible.
+    ACTIVITY_VISIBLE,
+    // The activity does not have gpu compositing layers, will not be visible
+    // and will be treated as a background priority task.
+    ACTIVITY_INVISIBLE,
+    // The activity should surrender additional resources. This has only an
+    // effect when the activity is in a loaded state (Visible, Active, Hidden).
+    ACTIVITY_BACKGROUND_LOW_PRIORITY,
+    // The activity will only keep a minimum set of resources to get back to the
+    // running state. It will get stalled however. Note that it is not possible
+    // to get into this state from the |ACTIVITY_UNLOADED| state.
+    ACTIVITY_PERSISTENT,
+    // Unloads the activity and can be called in any state - but unloaded.
+    ACTIVITY_UNLOADED
+  };
+
+  // This enum declares the media state the activity is in.
+  // TODO(skuhne): Move the |TabMediaState| out of chrome and combine it in a
+  // media library within content and then use that enum instead.
+  enum ActivityMediaState {
+    ACTIVITY_MEDIA_STATE_NONE,
+    ACTIVITY_MEDIA_STATE_RECORDING,  // Audio/Video being recorded by activity.
+    ACTIVITY_MEDIA_STATE_CAPTURING,  // Activity is being captured.
+    ACTIVITY_MEDIA_STATE_AUDIO_PLAYING  // Audible audio is playing in activity.
+  };
+
   virtual ~Activity();
 
   // The Activity retains ownership of the returned view-model.
   virtual ActivityViewModel* GetActivityViewModel() = 0;
+
+  // Transition the activity into a new state.
+  virtual void SetCurrentState(ActivityState state) = 0;
+
+  // Returns the current state of the activity.
+  virtual ActivityState GetCurrentState() = 0;
+
+  // Returns if the activity is visible or not.
+  virtual bool IsVisible() = 0;
+
+  // Returns the current media state.
+  virtual ActivityMediaState GetMediaState() = 0;
 };
 
 }  // namespace athena
 
 #endif  // ATHENA_ACTIVITY_PUBLIC_ACTIVITY_H_