nacl: Fix a bunch of compiler warnings

ipc/ipc_channel_nacl.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 "ipc/ipc_channel_nacl.h"
 
 #include <errno.h>
 #include <stddef.h>
 #include <sys/nacl_imc_api.h>
 #include <sys/nacl_syscalls.h>
@@ skipping 243 matching lines @@
   if (pipe_ == -1)
     return false;
 
   // Write out all the messages. The trusted implementation is guaranteed to not
   // block. See NaClIPCAdapter::Send for the implementation of imc_sendmsg.
   while (!output_queue_.empty()) {
     linked_ptr<Message> msg = output_queue_.front();
     output_queue_.pop_front();
 
     int fds[FileDescriptorSet::kMaxDescriptorsPerMessage];
-    const int num_fds = msg->file_descriptor_set()->size();
+    const size_t num_fds = msg->file_descriptor_set()->size();
     DCHECK(num_fds <= FileDescriptorSet::kMaxDescriptorsPerMessage);
     msg->file_descriptor_set()->GetDescriptors(fds);
 
     NaClImcMsgIoVec iov = { const_cast<void*>(msg->data()), msg->size() };
     NaClImcMsgHdr msgh = { &iov, 1, fds, num_fds };
     ssize_t bytes_written = imc_sendmsg(pipe_, &msgh, 0);
 
     DCHECK(bytes_written);  // The trusted side shouldn't return 0.
     if (bytes_written < 0) {
       // The trusted side should only ever give us an error of EPIPE. We
@@ skipping 20 matching lines @@
     char* buffer,
     int buffer_len,
     int* bytes_read) {
   *bytes_read = 0;
   if (pipe_ == -1)
     return READ_FAILED;
   if (read_queue_.empty())
     return READ_PENDING;
   while (!read_queue_.empty() && *bytes_read < buffer_len) {
     linked_ptr<std::vector<char> > vec(read_queue_.front());
-    int bytes_to_read = buffer_len - *bytes_read;
+    size_t bytes_to_read = buffer_len - *bytes_read;
     if (vec->size() <= bytes_to_read) {
       // We can read and discard the entire vector.
       std::copy(vec->begin(), vec->end(), buffer + *bytes_read);
       *bytes_read += vec->size();
       read_queue_.pop_front();
     } else {
       // Read all the bytes we can and discard them from the front of the
       // vector. (This can be slowish, since erase has to move the back of the
       // vector to the front, but it's hopefully a temporary hack and it keeps
       // the code simple).
@@ skipping 72 matching lines @@
   // A random name is sufficient validation on posix systems, so we don't need
   // an additional shared secret.
   std::string id = prefix;
   if (!id.empty())
     id.append(".");
 
   return id.append(GenerateUniqueRandomChannelID());
 }
 
 }  // namespace IPC