Further cleanup around DBus interface classes.

* Removed the "Glib" part from the various DbusGlib class name and added
  "Wrapper" instead: only part of the methods here declared have
  anything to do with Glib; in essence, this is an interface containing
  wrappers for various DBus functions.

* Changed "Dbus" to "DBus", to comply with the rest of the world.

* Renamed the actual implementation "RealDBusWrapper" (instead of
  "Concrete").

* Separated out RealDBusWrapper into its own header file. Client code,
  which often only cares about the abstract class, does not need to pull
  it unless specifically requiring it.

* Cleaned up the includes in these headers.

Aside from all that, also renamed system_state.cc into
real_system_state.cc, as this is what this file contains.

BUG=None
TEST=Unit tests.

Change-Id: I015c407cbc159aba8b5925eb0e916ba604c829cd
Reviewed-on: https://chromium-review.googlesource.com/189373
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/real_system_state.h b/real_system_state.h
index 4ff229d..7c411f8 100644
--- a/real_system_state.h
+++ b/real_system_state.h
@@ -5,16 +5,17 @@
 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_REAL_SYSTEM_STATE_H_
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_REAL_SYSTEM_STATE_H_
 
-#include <update_engine/system_state.h>
+#include "update_engine/system_state.h"
 
-#include <update_engine/clock.h>
-#include <update_engine/connection_manager.h>
-#include <update_engine/gpio_handler.h>
-#include <update_engine/hardware.h>
-#include <update_engine/payload_state.h>
-#include <update_engine/prefs.h>
-#include <update_engine/update_attempter.h>
-#include <update_engine/p2p_manager.h>
+#include "update_engine/clock.h"
+#include "update_engine/connection_manager.h"
+#include "update_engine/gpio_handler.h"
+#include "update_engine/hardware.h"
+#include "update_engine/payload_state.h"
+#include "update_engine/prefs.h"
+#include "update_engine/real_dbus_wrapper.h"
+#include "update_engine/update_attempter.h"
+#include "update_engine/p2p_manager.h"
 
 namespace chromeos_update_engine {
 
@@ -126,7 +127,7 @@
   scoped_ptr<GpioHandler> gpio_handler_;
 
   // The dbus object used to initialize the update attempter.
-  ConcreteDbusGlib dbus_;
+  RealDBusWrapper dbus_;
 
   // Pointer to the update attempter object.
   scoped_ptr<UpdateAttempter> update_attempter_;