buffet: Add ObjectManager interface to /org/chromium/Buffet

BUG=chromium:359190
TEST=`buffet_client GetManagedObjects` returns
message_type: MESSAGE_METHOD_RETURN
destination: :1.35
sender: :1.31
signature: a{oa{sa{sv}}}
serial: 10
reply_serial: 3

array [
  dict entry {
    object_path "/org/chromium/Buffet/Manager"
    array [
      dict entry {
        string "org.chromium.Buffet.Manager"
        array [
          dict entry {
            string "State"
            variant               string "{}"
          }
        ]
      }
    ]
  }
]

Done.

Change-Id: I2bbcc9a3f71c7ec6ab76cb4600dad7efe1a8bb0a
Reviewed-on: https://chromium-review.googlesource.com/198963
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Ilja Friedel <ihf@chromium.org>
diff --git a/buffet/main.cc b/buffet/main.cc
index e48a1b0..43ba4ab 100644
--- a/buffet/main.cc
+++ b/buffet/main.cc
@@ -16,9 +16,12 @@
 #include <sysexits.h>
 
 #include "buffet/async_event_sequencer.h"
+#include "buffet/dbus_constants.h"
+#include "buffet/exported_object_manager.h"
 #include "buffet/manager.h"
 
 using buffet::dbus_utils::AsyncEventSequencer;
+using buffet::dbus_utils::ExportedObjectManager;
 
 namespace {
 
@@ -87,7 +90,11 @@
 void EnterMainLoop(base::MessageLoopForIO* message_loop,
                    scoped_refptr<dbus::Bus> bus) {
   scoped_refptr<AsyncEventSequencer> sequencer(new AsyncEventSequencer());
-  buffet::Manager manager(bus.get());
+  ExportedObjectManager object_manager(
+      bus, dbus::ObjectPath(buffet::dbus_constants::kRootServicePath));
+  buffet::Manager manager(bus, object_manager.AsWeakPtr());
+  object_manager.Init(
+      sequencer->GetHandler("ObjectManager.Init() failed.", true));
   manager.Init(sequencer->GetHandler("Manager.Init() failed.", true));
   sequencer->OnAllTasksCompletedCall(
       {base::Bind(&TakeServiceOwnership, bus)});