Linux: use MessageLoopProxy instead of base::Thread in our DBus client library.

dbus/bus.h

Index: dbus/bus.h
===================================================================
--- dbus/bus.h	(revision 99574)
+++ dbus/bus.h	(working copy)
@@ -13,7 +13,6 @@
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "base/tracked_objects.h"
@@ -22,6 +21,7 @@
 
 namespace base {
 class Thread;
+class MessageLoopProxy;
 }
 
 namespace dbus {
@@ -79,9 +79,9 @@
 //       bus.GetObjectProxy(service_name, object_path);
 //
 //   dbus::MethodCall method_call(interface_name, method_name);
-//   dbus::Response response;
-//   bool success =
-//       object_proxy.CallMethodAndBlock(&method_call, timeout_ms, &response);
+//   scoped_ptr<dbus::Response> response(
+//       object_proxy.CallMethodAndBlock(&method_call, timeout_ms));
+//   bool success = !!response.get();

[satorux1, 2011/09/06 17:15:57]

Thank you for updating this!

!! is a bit tricky. Something like this may be more useful as example code:

  if (response.get()) {  // Success.
    ...

[Mike Mammarella, 2011/09/06 19:11:08]

Done.

 //
 // Asynchronous method call:
 //
@@ -154,14 +154,16 @@
 
     BusType bus_type;  // SESSION by default.
     ConnectionType connection_type;  // PRIVATE by default.
-    // If the thread is set, the bus object will use the message loop
-    // attached to the thread to process asynchronous operations.
+    // If dbus_thread is set, the bus object will use that message loop to
+    // process asynchronous operations. While the type of dbus_thread is
+    // MessageLoopProxy, this is only for convenience so it can be set with
+    // BrowserThread::GetMessageLoopProxyForThread().

[satorux1, 2011/09/06 17:15:57]

I like the idea of using MessageLoopProxy.

The name |dbus_thread| may be a bit irrelevant. It's a bit long but what about
dbus_thread_message_loop_proxy? Then, I think you can remove the excuse about
the type of dbus_thread.

[Mike Mammarella, 2011/09/06 19:11:08]

Done.

     //
     // The thread should meet the following requirements:
     // 1) Already running.
     // 2) Has a MessageLoopForIO.
     // 3) Outlives the bus.

[satorux1, 2011/09/06 17:15:57]

3) may be now irrelevant, as MessageLoopProxy takes care of the lifetime
problem.

[Mike Mammarella, 2011/09/06 19:11:08]

Done.

-    base::Thread* dbus_thread;  // NULL by default.
+    scoped_refptr<base::MessageLoopProxy> dbus_thread;  // NULL by default.
   };
 
   // Creates a Bus object. The actual connection will be established when
@@ -430,13 +432,12 @@
                                            void* data);
   const BusType bus_type_;
   const ConnectionType connection_type_;
-  base::Thread* dbus_thread_;
+  scoped_refptr<base::MessageLoopProxy> dbus_thread_;
   base::WaitableEvent on_shutdown_;
   DBusConnection* connection_;
 
   MessageLoop* origin_loop_;
   base::PlatformThreadId origin_thread_id_;
-  base::PlatformThreadId dbus_thread_id_;
 
   std::set<std::string> owned_service_names_;
   // The following sets are used to check if rules/object_paths/filters