arc: Revamp the ArcBridgeService interface

chrome/browser/chromeos/arc/gpu_arc_video_service_host.h

Index: chrome/browser/chromeos/arc/gpu_arc_video_service_host.h
diff --git a/chrome/browser/chromeos/arc/gpu_arc_video_service_host.h b/chrome/browser/chromeos/arc/gpu_arc_video_service_host.h
index 4fb2c67084a8006b4a7eecbf0a17d00a6d03c291..71f36ec8efd4a92e4ae6b8a4bfe7600da3dc24a1 100644
--- a/chrome/browser/chromeos/arc/gpu_arc_video_service_host.h
+++ b/chrome/browser/chromeos/arc/gpu_arc_video_service_host.h
@@ -10,6 +10,7 @@
 #include "components/arc/arc_bridge_service.h"
 #include "components/arc/arc_service.h"
 #include "components/arc/common/video.mojom.h"
+#include "components/arc/instance_holder.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace arc {
@@ -20,15 +21,16 @@ namespace arc {
 //
 // This class is the proxy end of GpuArcVideoService and runs in the browser
 // process. The corresponding end "GpuArcVideoService" runs in the GPU process.
-class GpuArcVideoServiceHost : public arc::ArcService,
-                               public arc::ArcBridgeService::Observer,
-                               public arc::mojom::VideoHost {
+class GpuArcVideoServiceHost
+    : public arc::ArcService,
+      public arc::InstanceHolder<mojom::VideoInstance>::Observer,
+      public arc::mojom::VideoHost {
  public:
   explicit GpuArcVideoServiceHost(arc::ArcBridgeService* bridge_service);
   ~GpuArcVideoServiceHost() override;
 
-  // arc::ArcBridgeService::Observer implementation.
-  void OnVideoInstanceReady() override;
+  // arc::InstanceHolder<mojom::VideoInstance>::Observer implementation.
+  void OnInstanceReady() override;
 
   // arc::mojom::VideoHost implementation.
   void DeprecatedOnRequestArcVideoAcceleratorChannel(