Enable size_t to int truncation warnings in PPAPI

ppapi/proxy/ppb_testing_proxy.cc

 // Copyright (c) 2012 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/ppb_testing_proxy.h"
 
 #include "base/message_loop/message_loop.h"
 #include "ppapi/c/private/ppb_testing_private.h"
 #include "ppapi/proxy/enter_proxy.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
@@ skipping 94 matching lines @@
 // host-side tracker when running out-of-process, to make sure the proxy does
 // not leak host-side vars.
 uint32_t GetLiveVars(PP_Var live_vars[], uint32_t array_size) {
   ProxyAutoLock lock;
   std::vector<PP_Var> vars =
       PpapiGlobals::Get()->GetVarTracker()->GetLiveVars();
   for (size_t i = 0u;
        i < std::min(static_cast<size_t>(array_size), vars.size());
        ++i)
     live_vars[i] = vars[i];
-  return vars.size();
+  return static_cast<uint32_t>(vars.size());
 }
 
 void SetMinimumArrayBufferSizeForShmem(PP_Instance instance,
                                        uint32_t threshold) {
   ProxyAutoLock lock;
   RawVarDataGraph::SetMinimumArrayBufferSizeForShmemForTest(threshold);
   PluginDispatcher* dispatcher = PluginDispatcher::GetForInstance(instance);
   if (!dispatcher)
     return;
   dispatcher->Send(
@@ skipping 89 matching lines @@
                                         input_event_impl->pp_resource());
 }
 
 void PPB_Testing_Proxy::OnMsgSetMinimumArrayBufferSizeForShmem(
     uint32_t threshold) {
   RawVarDataGraph::SetMinimumArrayBufferSizeForShmemForTest(threshold);
 }
 
 }  // namespace proxy
 }  // namespace ppapi