Coverity fixes for uninitialized vars

ppapi/proxy/plugin_var_tracker.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/proxy/plugin_var_tracker.h"
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/singleton.h"
 #include "ppapi/c/ppb_var.h"
 #include "ppapi/proxy/plugin_array_buffer_var.h"
@@ skipping 216 matching lines @@
 
 PP_Var PluginVarTracker::GetOrCreateObjectVarID(ProxyObjectVar* object) {
   // We can't use object->GetPPVar() because we don't want to affect the
   // refcount, so we have to add everything manually here.
   int32 var_id = object->GetExistingVarID();
   if (!var_id) {
     var_id = AddVarInternal(object, ADD_VAR_CREATE_WITH_NO_REFERENCE);
     object->AssignVarID(var_id);
   }
 
-  PP_Var ret;
-  ret.type = PP_VARTYPE_OBJECT;
+  PP_Var ret = { PP_VARTYPE_OBJECT };
   ret.value.as_id = var_id;
   return ret;
 }
 
 void PluginVarTracker::SendAddRefObjectMsg(
     const ProxyObjectVar& proxy_object) {
   int unused;
   proxy_object.dispatcher()->Send(new PpapiHostMsg_PPBVar_AddRefObject(
       API_ID_PPB_VAR_DEPRECATED, proxy_object.host_var_id(), &unused));
 }
@@ skipping 22 matching lines @@
   VarMap::iterator ret = live_vars_.find(found->second);
   DCHECK(ret != live_vars_.end());
 
   // All objects should be proxy objects.
   DCHECK(ret->second.var->AsProxyObjectVar());
   return scoped_refptr<ProxyObjectVar>(ret->second.var->AsProxyObjectVar());
 }
 
 }  // namesace proxy
 }  // namespace ppapi