Add status service for remoting host.

remoting/host/remoting_me2me_host.cc

Index: remoting/host/remoting_me2me_host.cc
diff --git a/remoting/host/remoting_me2me_host.cc b/remoting/host/remoting_me2me_host.cc
index 69b71cd23af00c1908f5582133a5efe00948a69b..883a1018e768ece4a99fedf17f77a881c11dcbd1 100644
--- a/remoting/host/remoting_me2me_host.cc
+++ b/remoting/host/remoting_me2me_host.cc
@@ -48,6 +48,7 @@
 #include "remoting/host/host_config.h"
 #include "remoting/host/host_event_logger.h"
 #include "remoting/host/host_exit_codes.h"
+#include "remoting/host/host_status_service.h"
 #include "remoting/host/host_user_interface.h"
 #include "remoting/host/ipc_consts.h"
 #include "remoting/host/ipc_desktop_environment_factory.h"
@@ -104,6 +105,9 @@ const char kVersionSwitchName[] = "version";
 // linux.
 const char kAudioPipeSwitchName[] = "audio-pipe-name";
 
+// The command line switch used to enable host status service.
+const char kEnableStatusServiceSwitchName[] = "enable-status-service";
+
 void QuitMessageLoop(MessageLoop* message_loop) {
   message_loop->PostTask(FROM_HERE, MessageLoop::QuitClosure());
 }
@@ -193,6 +197,8 @@ class HostProcess
   bool OnCurtainPolicyUpdate(bool curtain_required);
   bool OnHostTalkGadgetPrefixPolicyUpdate(const std::string& talkgadget_prefix);
 
+  void StartHostStatusService();
+
   void StartHost();
 
   void OnAuthFailed();
@@ -228,6 +234,9 @@ class HostProcess
   scoped_ptr<ConfigFileWatcher> config_watcher_;
 
   // Accessed on the network thread.
+
+  scoped_ptr<HostStatusService> status_service_;
+
   std::string host_id_;
   protocol::SharedSecretHash host_secret_hash_;
   HostKeyPair key_pair_;
@@ -495,6 +504,14 @@ void HostProcess::StartHostProcess() {
   }
 #endif  // defined(OS_LINUX)
 
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          kEnableStatusServiceSwitchName)) {
+    context_->network_task_runner()->PostTask(
+        FROM_HERE,
+        base::Bind(&HostProcess::StartHostStatusService,
+                   base::Unretained(this)));
+  }
+
   // Create a desktop environment factory appropriate to the build type &
   // platform.
 #if defined(OS_WIN)
@@ -765,6 +782,11 @@ bool HostProcess::OnHostTalkGadgetPrefixPolicyUpdate(
   return false;
 }
 
+void HostProcess::StartHostStatusService() {
+  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
+  status_service_.reset(new HostStatusService());
+}
+
 void HostProcess::StartHost() {
   DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
   DCHECK(!host_);
@@ -846,6 +868,9 @@ void HostProcess::StartHost() {
                           base::Unretained(this)));
   }
 
+  if (status_service_)
+    status_service_->SetHostIsUp(host_id_);
+
   host_->Start(xmpp_login_);
 
   CreateAuthenticatorFactory();
@@ -904,6 +929,9 @@ void HostProcess::Shutdown(int exit_code) {
   if (shutting_down_)
     return;
 
+  if (status_service_)
+    status_service_->SetHostIsDown();
+
   shutting_down_ = true;
   exit_code_ = exit_code;
   if (host_) {
@@ -928,6 +956,8 @@ void HostProcess::OnShutdownFinished() {
     policy_watcher_.reset();
   }
 
+  status_service_.reset();
+
   // Complete the rest of shutdown on the main thread.
   context_->ui_task_runner()->PostTask(
       FROM_HERE,