Implement GpuArcVideoService for arc video accelerator

components/arc/arc_bridge_service.h

Index: components/arc/arc_bridge_service.h
diff --git a/components/arc/arc_bridge_service.h b/components/arc/arc_bridge_service.h
index f3cc81f4cc9463eeb06462d2889581c7dae2baf8..ba074925dc3b47c728eb0bc401581cf858995bfa 100644
--- a/components/arc/arc_bridge_service.h
+++ b/components/arc/arc_bridge_service.h
@@ -78,6 +78,9 @@ class ArcBridgeService {
     // Called whenever ARC's availability has changed for this system.
     virtual void OnAvailableChanged(bool available) {}
 
+    // Called whenever the ARC video is ready.
+    virtual void OnVideoInstanceReady() {}
+
    protected:
     virtual ~Observer() {}
   };
@@ -170,6 +173,8 @@ class ArcBridgeService {
   void AddProcessObserver(ProcessObserver* observer);
   void RemoveProcessObserver(ProcessObserver* observer);
 
+  virtual VideoInstance* video_instance() = 0;
+
   // Gets the current state of the bridge service.
   State state() const { return state_; }