Enhance the DBus interface for peerd

Add ability to query properties of
 - Manager
 - Peer
 - Service
Add Observer to peerd so we are told when things change.

BUG=453873

Review URL: https://codereview.chromium.org/893663002

Cr-Commit-Position: refs/heads/master@{#315311}

chromeos/dbus/fake_peer_daemon_manager_client.cc

@@ -15,6 +15,32 @@ FakePeerDaemonManagerClient::~FakePeerDaemonManagerClient() {
 void FakePeerDaemonManagerClient::Init(dbus::Bus* bus) {
 }
 
+void FakePeerDaemonManagerClient::AddObserver(Observer* observer) {
+}
+
+void FakePeerDaemonManagerClient::RemoveObserver(Observer* observer) {
+}
+
+std::vector<dbus::ObjectPath> FakePeerDaemonManagerClient::GetPeers() {
+  return std::vector<dbus::ObjectPath>();
+}
+
+std::vector<dbus::ObjectPath> FakePeerDaemonManagerClient::GetServices() {
+  return std::vector<dbus::ObjectPath>();
+}
+
+PeerDaemonManagerClient::PeerProperties*
+FakePeerDaemonManagerClient::GetPeerProperties(
+    const dbus::ObjectPath& object_path) {
+  return nullptr;
+}
+
+PeerDaemonManagerClient::ServiceProperties*
+FakePeerDaemonManagerClient::GetServiceProperties(
+    const dbus::ObjectPath& object_path) {
+  return nullptr;
+}
+
 void FakePeerDaemonManagerClient::StartMonitoring(
     const std::vector<std::string>& requested_technologies,
     const base::DictionaryValue& options,

chromeos/dbus/fake_peer_daemon_manager_client.h

@@ -24,6 +24,14 @@ class FakePeerDaemonManagerClient : public PeerDaemonManagerClient {
   void Init(dbus::Bus* bus) override;
 
   // PeerDaemonManagerClient overrides:
+  void AddObserver(Observer* observer) override;
+  void RemoveObserver(Observer* observer) override;
+  std::vector<dbus::ObjectPath> GetPeers() override;
+  std::vector<dbus::ObjectPath> GetServices() override;
+  PeerProperties* GetPeerProperties(
+      const dbus::ObjectPath& object_path) override;
+  ServiceProperties* GetServiceProperties(
+      const dbus::ObjectPath& object_path) override;
   void StartMonitoring(const std::vector<std::string>& requested_technologies,
                        const base::DictionaryValue& options,
                        const StringDBusMethodCallback& callback) override;