[Chromoting] Implement the host domain policy.

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 15b79076ce4aa2726bc64a2b37d42d5bddf91a45..241abaa80a311283f655e1196fa04a5fc73ea51c 100644
--- a/remoting/host/remoting_me2me_host.cc
+++ b/remoting/host/remoting_me2me_host.cc
@@ -86,6 +86,14 @@ const char kOfficialOAuth2ClientId[] =
     "440925447803-avn2sj1kc099s0r7v62je5s339mu0am1.apps.googleusercontent.com";
 const char kOfficialOAuth2ClientSecret[] = "Bgur6DFiOMM1h8x-AQpuTQlK";
 
+// Whether a given string ends with a given suffix.
+bool EndsWith(std::string s, std::string suffix) {
+  if (s.length() < suffix.length()) {
+    return false;
+  }
+  return s.compare(s.length() - suffix.length(), suffix.length(), suffix) == 0;
+}
+
 }  // namespace
 
 namespace remoting {
@@ -323,12 +331,31 @@ class HostProcess
     }
 
     bool bool_value;
+    std::string string_value;
+    if (policies->GetString(policy_hack::PolicyWatcher::kHostDomainPolicyName,
+                            &string_value)) {
+      OnHostDomainPolicyUpdate(string_value);
+    }
     if (policies->GetBoolean(policy_hack::PolicyWatcher::kNatPolicyName,
                              &bool_value)) {
       OnNatPolicyUpdate(bool_value);
     }
   }
 
+  void OnHostDomainPolicyUpdate(const std::string& host_domain) {
+    if (!context_->network_task_runner()->BelongsToCurrentThread()) {
+      context_->network_task_runner()->PostTask(FROM_HERE, base::Bind(
+          &HostProcess::OnHostDomainPolicyUpdate, base::Unretained(this),
+          host_domain));
+      return;
+    }
+
+    if (!host_domain.empty() &&
+        !EndsWith(xmpp_login_, std::string("@") + host_domain)) {
+      Shutdown(kInvalidHostDomainExitCode);
+    }
+  }
+
   void OnNatPolicyUpdate(bool nat_traversal_enabled) {
     if (!context_->network_task_runner()->BelongsToCurrentThread()) {
       context_->network_task_runner()->PostTask(FROM_HERE, base::Bind(
@@ -355,6 +382,9 @@ class HostProcess
     DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
     DCHECK(!host_);
 
+    if (shutting_down_)
+      return;
+
     if (!signal_strategy_.get()) {
       signal_strategy_.reset(
           new XmppSignalStrategy(context_->url_request_context_getter(),
@@ -479,8 +509,12 @@ class HostProcess
 
     shutting_down_ = true;
     exit_code_ = exit_code;
-    host_->Shutdown(base::Bind(
-        &HostProcess::OnShutdownFinished, base::Unretained(this)));
+    if (host_) {
+      host_->Shutdown(base::Bind(
+          &HostProcess::OnShutdownFinished, base::Unretained(this)));
+    } else {
+      OnShutdownFinished();
+    }
   }
 
   void OnShutdownFinished() {