arc: Revamp the ArcBridgeService interface

chrome/browser/chromeos/arc/gpu_arc_video_service_host.h

 // Copyright 2016 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 CHROME_BROWSER_CHROMEOS_ARC_GPU_ARC_VIDEO_SERVICE_HOST_H_
 #define CHROME_BROWSER_CHROMEOS_ARC_GPU_ARC_VIDEO_SERVICE_HOST_H_
 
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #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 {
 
 // This class takes requests for creating channels of video accelerators from
 // arc::VideoInstance and forwards these requests to GpuArcVideoServce. It also
 // returns the created channels back to the arc::VideoInstance.
 //
 // 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(
       const DeprecatedOnRequestArcVideoAcceleratorChannelCallback& callback)
       override;
   void OnBootstrapVideoAcceleratorFactory(
       const OnBootstrapVideoAcceleratorFactoryCallback& callback) override;
 
  private:
   base::ThreadChecker thread_checker_;
 
   mojo::Binding<arc::mojom::VideoHost> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuArcVideoServiceHost);
 };
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_GPU_ARC_VIDEO_SERVICE_HOST_H_