Add proxies for Var deprecated and some additional tracking information. The...

Add proxies for Var deprecated and some additional tracking information.  These
don't build by themselves, this is part of a larger patch. You can see most of
the serialization mechanics already checked in to the same directory.

TEST=none
BUG=none

Committed: http://code.google.com/p/ppapi/source/detail?r=64955

[jam, 2010-11-03 17:21:22]

lgtm with these nits

http://codereview.chromium.org/4369001/diff/1/2
File ppapi/proxy/plugin_var_tracker.cc (right):

http://codereview.chromium.org/4369001/diff/1/2#newcode125
ppapi/proxy/plugin_var_tracker.cc:125: INTERFACE_ID_PPB_VAR_DEPRECATED, id));
nit: here and below, 2 extra spaces

http://codereview.chromium.org/4369001/diff/1/3
File ppapi/proxy/plugin_var_tracker.h (right):

http://codereview.chromium.org/4369001/diff/1/3#newcode23
ppapi/proxy/plugin_var_tracker.h:23: // a single ref in the browser process
whenever we have a nonzero refcount
browser->renderer to match the cc file?

http://codereview.chromium.org/4369001/diff/1/3#newcode62
ppapi/proxy/plugin_var_tracker.h:62: // When !is_plugin_ (we're in the renderer)
this points to the actual var
there's no is_plugin_ here?

http://codereview.chromium.org/4369001/diff/1/4
File ppapi/proxy/ppb_var_deprecated_proxy.cc (right):

http://codereview.chromium.org/4369001/diff/1/4#newcode274
ppapi/proxy/ppb_var_deprecated_proxy.cc:274: // FIXME(brettw) handle bad
messages!
nit: now that this is in chrome repo, shouldn't it be TODO?