Use MetaGroup for a window when looking up applications. If
we know the application for a TYPE_NORMAL window in the group,
use that.
However, we aren't always going to know the application for a window. In
that case, create a fake one.
ShellAppInfo has a "transient" flag so we know not to write these
fake apps to the usage file.
Clean up the idle focus handler to better handle the case where
no window is focused, and where we don't want to track the
particular window.
Update track_window to create the fake window.
When a window goes away, we want to delete the usage.
Rewrite shell_app_monitor_get_running_apps to be based
on the window_to_app hash, because that's what has the pointer
to ShellAppInfo*. Before we were looking up all ids through
ShellAppSystem, but that shouldn't be holding a ref to transients.
Change the well display icon to be centered, since our icons for
window apps aren't 48 pixels.
a4bf54e465