Bug 927459: Cleanup DBusThread, r=qdot

This patch renames DBusThread to DBusWatcher to make its purpose
more clear. Several callback functions for DBus are converted to
methods of DBusWatcher. Their POSIX calls are now protected by
TEMP_FAILURE_RETRY.

--HG--
extra : rebase_source : d8c6963aa8388c462917180d78e8e4289f9e987a
Bug 927459: Move poll functionality to DBusWatcher, r=qdot

The DBus poll functionality is actually part of DBusWatcher. This
patch moves it to a class method.

--HG--
extra : rebase_source : 012813cf1d0967d6c29f7e085e49940570e1d58d
Bug 927459: Add DBusWatcher::Stop, r=qdot

The Stop method encapsulates the code for sending the exit command
to a running DBus watcher.

--HG--
extra : rebase_source : 6963e6fa60b2e1e725046672a45cd325fc40a836
Bug 927459: Move helpers to DBusWatcher, r=qdot

PollFdComparator, DBusEventTypes and flag conversion are only used by
DBusWatcher. This patch moves them into DBusWatcher's namespace.

--HG--
extra : rebase_source : 688403e55e139440e6d6d28e9802f8a48d7c355d
Bug 927859: Cleanup DBus thread after DBusWatcher, r=qdot

This patch changes the DBus shutdown to only cleanup the DBus
thread from the main thread after DBusWatcher has completed.
This should ensure that the main thread will not have to wait
for the DBus thread.

--HG--
extra : rebase_source : 09ebb40a4e515ef5b0ebddfc1c3b7187cc546313