arc-bridge: Introduce the ArcService class

Several services managed by ARC were introducing empty, opaque classes
just to be able to be constructed outside of components/. This was
becoming ugly, so introduce just one interface that all services must
implement and whose lifecycle will be managed by ArcServiceManager.

BUG=None
TEST=trybots

Review URL: https://codereview.chromium.org/1596663002

Cr-Commit-Position: refs/heads/master@{#370825}

2 files changed, 15 insertions, 28 deletions

diff --git a/components/arc/video/arc_video_bridge.cc b/components/arc/video/arc_video_bridge.cc
index dddbb39..a57f775 100644
--- a/components/arc/video/arc_video_bridge.cc
+++ b/components/arc/video/arc_video_bridge.cc
@@ -9,25 +9,16 @@
 namespace arc {
 
 ArcVideoBridge::ArcVideoBridge(
+    ArcBridgeService* bridge_service,
     scoped_ptr<VideoHostDelegate> video_host_delegate)
-    : video_host_delegate_(std::move(video_host_delegate)),
-      binding_(video_host_delegate_.get()) {}
-
-ArcVideoBridge::~ArcVideoBridge() {
-  arc::ArcBridgeService* bridge_service = arc::ArcBridgeService::Get();
-  DCHECK(bridge_service);
-  bridge_service->RemoveObserver(this);
+    : ArcService(bridge_service),
+      video_host_delegate_(std::move(video_host_delegate)),
+      binding_(video_host_delegate_.get()) {
+  arc_bridge_service()->AddObserver(this);
 }
 
-void ArcVideoBridge::StartObservingBridgeServiceChanges() {
-  arc::ArcBridgeService* bridge_service = arc::ArcBridgeService::Get();
-  DCHECK(bridge_service);
-  bridge_service->AddObserver(this);
-
-  // If VideoInstance was ready before we AddObserver(), we won't get
-  // OnVideoInstanceReady events. For such case, we have to call it explicitly.
-  if (bridge_service->video_instance())
-    OnVideoInstanceReady();
+ArcVideoBridge::~ArcVideoBridge() {
+  arc_bridge_service()->RemoveObserver(this);
 }
 
 void ArcVideoBridge::OnStateChanged(arc::ArcBridgeService::State state) {
@@ -41,12 +32,9 @@ void ArcVideoBridge::OnStateChanged(arc::ArcBridgeService::State state) {
 }
 
 void ArcVideoBridge::OnVideoInstanceReady() {
-  arc::ArcBridgeService* bridge_service = arc::ArcBridgeService::Get();
-  DCHECK(bridge_service);
-
   arc::VideoHostPtr host;
   binding_.Bind(mojo::GetProxy(&host));
-  bridge_service->video_instance()->Init(std::move(host));
+  arc_bridge_service()->video_instance()->Init(std::move(host));
 }
 
 }  // namespace arc
diff --git a/components/arc/video/arc_video_bridge.h b/components/arc/video/arc_video_bridge.h
index f781a5e..bf1bd38 100644
--- a/components/arc/video/arc_video_bridge.h
+++ b/components/arc/video/arc_video_bridge.h
@@ -2,12 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef COMPONENTS_ARC_VIDEO_ARC_VIDEO_BRIDGE_H
-#define COMPONENTS_ARC_VIDEO_ARC_VIDEO_BRIDGE_H
+#ifndef COMPONENTS_ARC_VIDEO_ARC_VIDEO_BRIDGE_H_
+#define COMPONENTS_ARC_VIDEO_ARC_VIDEO_BRIDGE_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/arc/arc_bridge_service.h"
+#include "components/arc/arc_service.h"
 #include "components/arc/video/video_host_delegate.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
@@ -17,14 +18,12 @@ class VideoHostDelegate;
 
 // ArcVideoBridge bridges ArcBridgeService and VideoHostDelegate. It observes
 // ArcBridgeService events and pass VideoHost proxy to VideoInstance.
-class ArcVideoBridge : public ArcBridgeService::Observer {
+class ArcVideoBridge : public ArcService, public ArcBridgeService::Observer {
  public:
-  explicit ArcVideoBridge(scoped_ptr<VideoHostDelegate> video_host_delegate);
+  ArcVideoBridge(ArcBridgeService* bridge_service,
+                 scoped_ptr<VideoHostDelegate> video_host_delegate);
   ~ArcVideoBridge() override;
 
-  // Starts listening to state changes of the ArcBridgeService.
-  void StartObservingBridgeServiceChanges();
-
   // arc::ArcBridgeService::Observer implementation.
   void OnStateChanged(arc::ArcBridgeService::State state) override;
   void OnVideoInstanceReady() override;
@@ -38,4 +37,4 @@ class ArcVideoBridge : public ArcBridgeService::Observer {
 
 }  // namespace arc
 
-#endif  // COMPONENTS_ARC_VIDEO_ARC_VIDEO_BRIDGE_H
+#endif  // COMPONENTS_ARC_VIDEO_ARC_VIDEO_BRIDGE_H_