[GRC] Coordination Unit Graph Observer

services/resource_coordinator/coordination_unit/coordination_unit_graph_observer.h

 // Copyright 2017 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 SERVICES_RESOURCE_COORDINATOR_COORDINATION_UNIT_COORDINATION_UNIT_GRAPH_OBSERVER_H_
 #define SERVICES_RESOURCE_COORDINATOR_COORDINATION_UNIT_COORDINATION_UNIT_GRAPH_OBSERVER_H_
 
 #include <memory>
 #include <unordered_map>
 
 #include "base/macros.h"
 #include "services/resource_coordinator/coordination_unit/coordination_unit_impl.h"
 #include "services/resource_coordinator/public/cpp/coordination_unit_id.h"
 #include "services/resource_coordinator/public/cpp/coordination_unit_types.h"
 #include "services/resource_coordinator/public/interfaces/coordination_unit.mojom.h"
 
 namespace resource_coordinator {
 
-// An observer API for the CoordinationUnitGraph maintained by GRC.
+// An observer API for the coordination unit graph maintained by GRC.
 //
-// Observers are instantiated when the resource_coordinator serivce
+// Observers are instantiated when the resource_coordinator service
 // is created and are destroyed when the resource_coordinator service
 // is destroyed. Therefore observers are guaranteed to be alive before
 // any coordination unit is created and will be alive after any
 // coordination unit is destroyed. Additionally, any
 // Coordination Unit reachable within a callback will always be
 // initialized and valid.
 //
 // To create and install a new observer:
 //   (1) derive from this class
 //   (2) register in CoordinationUnitManager::RegisterObserver
 //       inside of CoordinationUnitManager::CoordinationUnitManager
-//
 class CoordinationUnitGraphObserver {
  public:
   CoordinationUnitGraphObserver();
-  // The CoordinationUnitGraphObserver will only call
-  // CoordinationUnitGraphObserver::CoordinationUnitCreated when the
-  // CoordinationUnit's CoordinationUnitID.type matches filter.
-  explicit CoordinationUnitGraphObserver(CoordinationUnitType filter);
   virtual ~CoordinationUnitGraphObserver();
 
-  // Determines whether or not OnCoordinationUnitCreated should be
-  // invoked on the newly created CoordinationUnit.
-  bool ShouldObserve(CoordinationUnitImpl* coordination_unit);
+  // Determines whether or not the observer should be registered and
+  // invoked for the |coordination_unit|.
+  virtual bool ShouldObserve(const CoordinationUnitImpl* coordination_unit) = 0;
 
-  // Called whenever any new CoordinationUnit of interest is created
-  // (i.e. ShouldObserve evaluates to true).
-  virtual void OnCoordinationUnitCreatedEvent(
-      CoordinationUnitImpl* coordination_unit) {}
+  // Called whenever a CoordinationUnit is created.
+  virtual void OnCoordinationUnitCreated(
+      const CoordinationUnitImpl* coordination_unit) {}
 
   // Called whenever a new parent-child relationship occurs where the
-  // |coordination_unit| is the parent and the |child_coordination_unit|
-  // type matches the CoordinationUnitType filter that the observer
-  // was registered with (e.g. CoordinationUnit::ObserveAddChildEvent).
-  virtual void OnChildAddedEvent(
+  // |coordination_unit| is the parent of |child_coordination_unit|
+  virtual void OnChildAdded(
       const CoordinationUnitImpl* coordination_unit,
       const CoordinationUnitImpl* child_coordination_unit) {}
 
   // Called whenever a new parent-child relationship occurs where the
-  // |coordination_unit| is the child and the |parent_coordination_unit|
-  // type matches the CoordinationUnitType filter that the observer
-  // was registered with (e.g. CoordinationUnit::ObserveAddParentEvent).
-  virtual void OnParentAddedEvent(
+  // |coordination_unit| is the child of |parent_coordination_unit|.
+  virtual void OnParentAdded(
       const CoordinationUnitImpl* coordination_unit,
       const CoordinationUnitImpl* parent_coordination_unit) {}
 
-  // Called whenever a |property| within the |coordination_unit|'s internal
-  // property store changes and the |property| type matches the
-  // mojom::Property filter that the observer was registered with
-  // (e.g. CoordinationUnit::ObservePropertyChangedEvent).
-  virtual void OnPropertyChangedEvent(
-      const CoordinationUnitImpl* coordination_unit,
-      mojom::PropertyType property) {}
+  // Called whenever a |property| within the |coordination_unit|'s
+  // internal property store has changed.
+  virtual void OnPropertyChanged(const CoordinationUnitImpl* coordination_unit,
+                                 mojom::PropertyType property) {}
 
   // Called whenever parent-child relationship ends where the
-  // |coordination_unit| was the parent and the |child_coordination_unit|
-  // type matches the CoordinationUnitType filter that the observer
-  // was registered with (e.g. CoordinationUnit::ObserveAddChildEvent).
-  virtual void OnChildRemovedEvent(
+  // |coordination_unit| was the parent and the |child_coordination_unit|.
+  virtual void OnChildRemoved(
       const CoordinationUnitImpl* coordination_unit,
       const CoordinationUnitImpl* child_coordination_unit) {}
 
   // Called whenever parent-child relationship ends where the
-  // |coordination_unit| was the child and the |child_coordination_unit|
-  // type matches the CoordinationUnitType filter that the observer
-  // was registered with (e.g. CoordinationUnit::ObserveRemoveParentEvent).
-  virtual void OnParentRemovedEvent(
+  // |coordination_unit| was the child and the |child_coordination_unit|.
+  virtual void OnParentRemoved(
       const CoordinationUnitImpl* coordination_unit,
       const CoordinationUnitImpl* parent_coordination_unit) {}
 
   // Called when the |coordination_unit| is about to be destroyed.
-  virtual void OnWillBeDestroyedEvent(
+  virtual void OnCoordinationUnitWillBeDestroyed(
       const CoordinationUnitImpl* coordination_unit) {}
 
- protected:
-  CoordinationUnitType filter_;
-
  private:
   DISALLOW_COPY_AND_ASSIGN(CoordinationUnitGraphObserver);
 };
 
 }  // namespace resource_coordinator
 
 #endif  // SERVICES_RESOURCE_COORDINATOR_COORDINATION_UNIT_COORDINATION_UNIT_GRAPH_OBSERVER_H_