buffet: Remove DBusManager class

Move the TestMethod to the Manager, then remove the DBusManager
entirely.  This lets us turn the object at org/chromium/Buffet
into a pure object manager and removes a lot of boilerplate.

BUG=chromium:359190
TEST=buffet_client continues to demonstrate buffet functionality
through the TestMethod, which is now implementated by the Manager.

Change-Id: Ie9ecf0f7dd4dd50a3355ad7b06b8e2cfca71d9f9
Reviewed-on: https://chromium-review.googlesource.com/198760
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/dbus_constants.cc b/buffet/dbus_constants.cc
index f352bbe..d8c70ba 100644
--- a/buffet/dbus_constants.cc
+++ b/buffet/dbus_constants.cc
@@ -10,11 +10,8 @@
 
 const char kServiceName[] = "org.chromium.Buffet";
 
-const char kRootInterface[] = "org.chromium.Buffet";
 const char kRootServicePath[] = "/org/chromium/Buffet";
 
-const char kRootTestMethod[] = "TestMethod";
-
 const char kManagerInterface[] = "org.chromium.Buffet.Manager";
 const char kManagerServicePath[] = "/org/chromium/Buffet/Manager";
 
@@ -23,6 +20,7 @@
 const char kManagerStartRegisterDevice[]    = "StartRegisterDevice";
 const char kManagerFinishRegisterDevice[]   = "FinishRegisterDevice";
 const char kManagerUpdateStateMethod[]      = "UpdateState";
+const char kManagerTestMethod[]             = "TestMethod";
 
 }  // namespace dbus_constants