Enable size_t to int truncation warnings in PPAPI

ppapi/proxy/ppapi_command_buffer_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/ppapi_command_buffer_proxy.h"
 
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/proxy_channel.h"
 #include "ppapi/shared_impl/api_id.h"
 #include "ppapi/shared_impl/host_resource.h"
@@ skipping 104 matching lines @@
   *id = -1;
 
   if (last_state_.error != gpu::error::kNoError)
     return NULL;
 
   // Assuming we are in the renderer process, the service is responsible for
   // duplicating the handle. This might not be true for NaCl.
   ppapi::proxy::SerializedHandle handle(
       ppapi::proxy::SerializedHandle::SHARED_MEMORY);
   if (!Send(new PpapiHostMsg_PPBGraphics3D_CreateTransferBuffer(
-            ppapi::API_ID_PPB_GRAPHICS_3D, resource_, size, id, &handle))) {
+            ppapi::API_ID_PPB_GRAPHICS_3D, resource_,
+            static_cast<uint32_t>(size), id, &handle))) {
     return NULL;
   }
 
   if (*id <= 0 || !handle.is_shmem())
     return NULL;
 
   scoped_ptr<base::SharedMemory> shared_memory(
       new base::SharedMemory(handle.shmem(), false));
 
   // Map the shared memory on demand.
@@ skipping 118 matching lines @@
     shared_state()->Read(&last_state_);
 }
 
 gpu::CommandBufferSharedState* PpapiCommandBufferProxy::shared_state() const {
   return reinterpret_cast<gpu::CommandBufferSharedState*>(
       shared_state_shm_->memory());
 }
 
 }  // namespace proxy
 }  // namespace ppapi