Enable size_t to int truncation warnings in PPAPI

ppapi/proxy/ppb_video_decoder_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_video_decoder_proxy.h"
 
 #include "base/logging.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
 #include "ppapi/proxy/enter_proxy.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
@@ skipping 229 matching lines @@
   PP_VideoBitstreamBuffer_Dev bitstream = { id, buffer.host_resource(), size };
   enter.SetResult(enter.object()->Decode(&bitstream, enter.callback()));
 }
 
 void PPB_VideoDecoder_Proxy::OnMsgAssignPictureBuffers(
     const HostResource& decoder,
     const std::vector<PP_PictureBuffer_Dev>& buffers) {
   EnterHostFromHostResource<PPB_VideoDecoder_Dev_API> enter(decoder);
   if (enter.succeeded() && !buffers.empty()) {
     const PP_PictureBuffer_Dev* buffer_array = &buffers.front();
-    enter.object()->AssignPictureBuffers(buffers.size(), buffer_array);
+    enter.object()->AssignPictureBuffers(
+        static_cast<uint32_t>(buffers.size()), buffer_array);
   }
 }
 
 void PPB_VideoDecoder_Proxy::OnMsgReusePictureBuffer(
     const HostResource& decoder, int32 picture_buffer_id) {
   EnterHostFromHostResource<PPB_VideoDecoder_Dev_API> enter(decoder);
   if (enter.succeeded())
     enter.object()->ReusePictureBuffer(picture_buffer_id);
 }
 
@@ skipping 53 matching lines @@
 
 void PPB_VideoDecoder_Proxy::OnMsgResetACK(
     const HostResource& decoder, int32_t result) {
   EnterPluginFromHostResource<PPB_VideoDecoder_Dev_API> enter(decoder);
   if (enter.succeeded())
     static_cast<VideoDecoder*>(enter.object())->ResetACK(result);
 }
 
 }  // namespace proxy
 }  // namespace ppapi