arc: support receiving notification of arc stopped from upstart job

Add support for receiving the signal that the ARC++ container has
stopped from an Upstart Job script. After the change on the ChromeOS side
is made to send the stopped signal from the job script instead of from
session_manager, support for receiving the signal from session_manager
will be removed.

Bug: b:133248517
Change-Id: I932778fde1f14a0581c96f0efb4f28892e991b8b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1673862
Commit-Queue: Chris Morin <cmtm@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672225}

chromeos/dbus/upstart/fake_upstart_client.cc

@@ -28,6 +28,9 @@ FakeUpstartClient::~FakeUpstartClient() {
   g_instance = nullptr;
 }
 
+void FakeUpstartClient::AddObserver(Observer* observer) {}
+void FakeUpstartClient::RemoveObserver(Observer* observer) {}
+
 // static
 FakeUpstartClient* FakeUpstartClient::Get() {
   return g_instance;

chromeos/dbus/upstart/fake_upstart_client.h

@@ -17,6 +17,10 @@ class COMPONENT_EXPORT(UPSTART_CLIENT) FakeUpstartClient
   FakeUpstartClient();
   ~FakeUpstartClient() override;
 
+  // Adds or removes an observer.
+  void AddObserver(Observer* observer) override;
+  void RemoveObserver(Observer* observer) override;
+
   // Returns the fake global instance if initialized. May return null.
   static FakeUpstartClient* Get();
 

chromeos/dbus/upstart/upstart_client.cc

@@ -10,6 +10,7 @@
 #include "dbus/bus.h"
 #include "dbus/message.h"
 #include "dbus/object_proxy.h"
+#include "third_party/cros_system_api/dbus/service_constants.h"
 
 namespace chromeos {
 
@@ -35,10 +36,27 @@ UpstartClient* g_instance = nullptr;
 class UpstartClientImpl : public UpstartClient {
  public:
   explicit UpstartClientImpl(dbus::Bus* bus)
-      : bus_(bus), weak_ptr_factory_(this) {}
+      : bus_(bus), weak_ptr_factory_(this) {
+    dbus::ObjectProxy* arc_proxy = bus_->GetObjectProxy(
+        arc::kArcServiceName, dbus::ObjectPath(arc::kArcServicePath));
+    arc_proxy->ConnectToSignal(
+        arc::kArcInterfaceName, arc::kArcStopped,
+        base::Bind(&UpstartClientImpl::ArcStoppedReceived,
+                   weak_ptr_factory_.GetWeakPtr()),
+        base::Bind(&UpstartClientImpl::SignalConnected,
+                   weak_ptr_factory_.GetWeakPtr()));
+  }
 
   ~UpstartClientImpl() override = default;
 
+  void AddObserver(Observer* observer) override {
+    observers_.AddObserver(observer);
+  }
+
+  void RemoveObserver(Observer* observer) override {
+    observers_.RemoveObserver(observer);
+  }
+
   // UpstartClient overrides:
   void StartJob(const std::string& job,
                 const std::vector<std::string>& upstart_env,
@@ -102,12 +120,26 @@ class UpstartClientImpl : public UpstartClient {
                        weak_ptr_factory_.GetWeakPtr(), std::move(callback)));
   }
 
+  // Called when the object is connected to the signal.
+  void SignalConnected(const std::string& interface_name,
+                       const std::string& signal_name,
+                       bool success) {
+    LOG_IF(ERROR, !success) << "Failed to connect to " << signal_name;
+  }
+
+  void ArcStoppedReceived(dbus::Signal* signal) {
+    for (auto& observer : observers_)
+      observer.ArcStopped();
+  }
+
   void OnVoidMethod(VoidDBusMethodCallback callback, dbus::Response* response) {
     std::move(callback).Run(response);
   }
 
   dbus::Bus* bus_ = nullptr;
 
+  base::ObserverList<Observer> observers_;
+
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<UpstartClientImpl> weak_ptr_factory_;

chromeos/dbus/upstart/upstart_client.h

@@ -11,6 +11,7 @@
 #include "base/callback.h"
 #include "base/component_export.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 
 namespace dbus {
@@ -24,6 +25,13 @@ namespace chromeos {
 // initializes the DBusThreadManager instance.
 class COMPONENT_EXPORT(UPSTART_CLIENT) UpstartClient {
  public:
+  class Observer : public base::CheckedObserver {
+   public:
+    ~Observer() override {}
+    // Called when the ARC is stopped after it had already started.
+    virtual void ArcStopped() {}
+  };
+
   virtual ~UpstartClient();
 
   // Creates and initializes the global instance. |bus| must not be null.
@@ -38,6 +46,10 @@ class COMPONENT_EXPORT(UPSTART_CLIENT) UpstartClient {
   // Returns the global instance if initialized. May return null.
   static UpstartClient* Get();
 
+  // Adds or removes an observer.
+  virtual void AddObserver(Observer* observer) = 0;
+  virtual void RemoveObserver(Observer* observer) = 0;
+
   // Starts an Upstart job.
   // |job|: Name of Upstart job.
   // |upstart_env|: List of upstart environment variables to be passed to the

components/arc/session/arc_container_client_adapter.cc

@@ -12,21 +12,27 @@
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "chromeos/dbus/login_manager/arc.pb.h"
 #include "chromeos/dbus/session_manager/session_manager_client.h"
+#include "chromeos/dbus/upstart/upstart_client.h"
 
 namespace arc {
 
 class ArcContainerClientAdapter
     : public ArcClientAdapter,
-      public chromeos::SessionManagerClient::Observer {
+      public chromeos::SessionManagerClient::Observer,
+      public chromeos::UpstartClient::Observer {
  public:
   ArcContainerClientAdapter() {
     if (chromeos::SessionManagerClient::Get())
       chromeos::SessionManagerClient::Get()->AddObserver(this);
+    if (chromeos::UpstartClient::Get())
+      chromeos::UpstartClient::Get()->AddObserver(this);
   }
 
   ~ArcContainerClientAdapter() override {
     if (chromeos::SessionManagerClient::Get())
       chromeos::SessionManagerClient::Get()->RemoveObserver(this);
+    if (chromeos::UpstartClient::Get())
+      chromeos::UpstartClient::Get()->RemoveObserver(this);
   }
 
   // ArcClientAdapter overrides:
@@ -57,6 +63,12 @@ class ArcContainerClientAdapter
       observer.ArcInstanceStopped();
   }
 
+  // chromeos::UpstartClient::Observer overrides:
+  void ArcStopped() override {
+    for (auto& observer : observer_list_)
+      observer.ArcInstanceStopped();
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ArcContainerClientAdapter);
 };