Switch from Delegate to Observer.

components/arc/arc_bridge_service_impl.cc

 // Copyright 2015 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.
 
 #include "components/arc/arc_bridge_service_impl.h"
 
 #include <string>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/json/json_writer.h"
 #include "base/message_loop/message_loop.h"
 #include "base/sequenced_task_runner.h"
 #include "base/sys_info.h"
 #include "base/task_runner_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "chromeos/chromeos_switches.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
-#include "components/arc/arc_bridge_host_impl.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
 
 namespace arc {
 
 extern ArcBridgeService* g_arc_bridge_service;
 
 namespace {
 constexpr int64_t kReconnectDelayInSeconds = 5;
 }  // namespace
 
 ArcBridgeServiceImpl::ArcBridgeServiceImpl()
     : session_started_(false),
       factory_(base::Bind(ArcBridgeBootstrap::Create)),
       weak_factory_(this) {
   DCHECK(!g_arc_bridge_service);
   g_arc_bridge_service = this;
 }
 
 ArcBridgeServiceImpl::~ArcBridgeServiceImpl() {
+  if (bootstrap_)
+    bootstrap_->RemoveObserver(this);
+
   DCHECK(g_arc_bridge_service == this);
   g_arc_bridge_service = nullptr;
 }
 
 void ArcBridgeServiceImpl::HandleStartup() {
   DCHECK(CalledOnValidThread());
   if (session_started_)
     return;
   VLOG(1) << "Session started";
   session_started_ = true;
@@ skipping 25 matching lines @@
   VLOG(1) << "Prerequisites changed. "
           << "state=" << static_cast<uint32_t>(state())
           << ", session_started=" << session_started_;
   if (state() == State::STOPPED) {
     if (!session_started_)
       return;
     VLOG(0) << "Prerequisites met, starting ARC";
     SetStopReason(StopReason::SHUTDOWN);
 
     SetState(State::CONNECTING);
     bootstrap_ = factory_.Run();

[Luis Héctor Chávez, 2016/10/03 18:05:32]

Should you unregister the previous bootstrap here if it exists? Otherwise
there'll be a DCHECK that its observer list is non-empty. Or is there a
guarantee that OnStopped will definitely be called before? If there is (e.g.
successive Shutdown()/HandleStartup() calls being guarded by ArcAuthService or
something like that), please document it here.

[hidehiko, 2016/10/04 05:34:45]

Added RemoveObserver, which is much safer.

-    bootstrap_->set_delegate(this);
+    bootstrap_->AddObserver(this);
     bootstrap_->Start();
   } else {
     if (session_started_)
       return;
     VLOG(0) << "Prerequisites stopped being met, stopping ARC";
     StopInstance();
   }
 }
 
 void ArcBridgeServiceImpl::StopInstance() {
   DCHECK(CalledOnValidThread());
   if (state() == State::STOPPED || state() == State::STOPPING) {
     VLOG(1) << "StopInstance() called when ARC is not running";
     return;
   }
 
   // We were explicitly asked to stop, so do not reconnect.
   reconnect_ = false;
 
   VLOG(1) << "Stopping ARC";
   DCHECK(bootstrap_.get());
   SetState(State::STOPPING);
-  arc_bridge_host_.reset();
 
   // Note: this can call OnStopped() internally as a callback.
   bootstrap_->Stop();
 }
 
-void ArcBridgeServiceImpl::OnConnectionEstablished(
-    mojom::ArcBridgeInstancePtr instance) {
+void ArcBridgeServiceImpl::OnReady() {
   DCHECK(CalledOnValidThread());
   if (state() != State::CONNECTING) {
     VLOG(1) << "StopInstance() called while connecting";
     return;
   }
 
-  arc_bridge_host_.reset(new ArcBridgeHostImpl(std::move(instance)));
-
   // The container can be considered to have been successfully launched, so
   // restart if the connection goes down without being requested.
   reconnect_ = true;
   VLOG(0) << "ARC ready";
   SetState(State::READY);
 }
 
 void ArcBridgeServiceImpl::OnStopped(StopReason stop_reason) {
   DCHECK(CalledOnValidThread());
   VLOG(0) << "ARC stopped: " << stop_reason;
-  arc_bridge_host_.reset();
+  bootstrap_->RemoveObserver(this);
   bootstrap_.reset();
   SetStopReason(stop_reason);
   SetState(State::STOPPED);
 
   if (reconnect_) {
     // There was a previous invocation and it crashed for some reason. Try
     // starting the container again.
     reconnect_ = false;
     VLOG(0) << "ARC reconnecting";
     if (use_delay_before_reconnecting_) {
       // Instead of immediately trying to restart the container, give it some
       // time to finish tearing down in case it is still in the process of
       // stopping.
       base::MessageLoop::current()->task_runner()->PostDelayedTask(
           FROM_HERE, base::Bind(&ArcBridgeServiceImpl::PrerequisitesChanged,
                                 weak_factory_.GetWeakPtr()),
           base::TimeDelta::FromSeconds(kReconnectDelayInSeconds));
     } else {
       // Restart immediately.
       PrerequisitesChanged();
     }
   }
 }
 
 }  // namespace arc