[mojo] Add CreateSharedBuffer method to Broker.

mojo/edk/embedder/platform_channel_utils_posix.cc

 // Copyright 2014 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 "mojo/edk/embedder/platform_channel_utils_posix.h"
 
 #include <stddef.h>
 #include <sys/socket.h>
 #include <sys/uio.h>
 #include <unistd.h>
@@ skipping 129 matching lines @@
   }
 
   for (size_t i = 0; i < num_handles; i++)
     handles[i].CloseIfNecessary();
   return true;
 }
 
 ssize_t PlatformChannelRecvmsg(PlatformHandle h,
                                void* buf,
                                size_t num_bytes,
-                               std::deque<PlatformHandle>* platform_handles) {
+                               std::deque<PlatformHandle>* platform_handles,
+                               bool should_block) {
   DCHECK(buf);
   DCHECK_GT(num_bytes, 0u);
   DCHECK(platform_handles);
 
   struct iovec iov = {buf, num_bytes};
   char cmsg_buf[CMSG_SPACE(kPlatformChannelMaxNumHandles * sizeof(int))];
   struct msghdr msg = {};
   msg.msg_iov = &iov;
   msg.msg_iovlen = 1;
   msg.msg_control = cmsg_buf;
   msg.msg_controllen = sizeof(cmsg_buf);
 
   // We use SO_PEEK_OFF to hold a common identifier between sockets to detect if
   // they're connected. recvmsg modifies it, so we cache it and set it again
   // after the call.
   int id = 0;
   socklen_t peek_off_size = sizeof(id);
   getsockopt(h.handle, SOL_SOCKET, SO_PEEK_OFF, &id, &peek_off_size);
-  ssize_t result = HANDLE_EINTR(recvmsg(h.handle, &msg, MSG_DONTWAIT));
+  ssize_t result =
+      HANDLE_EINTR(recvmsg(h.handle, &msg, should_block ? 0 : MSG_DONTWAIT));
   if (result < 0)
     return result;
 
   setsockopt(h.handle, SOL_SOCKET, SO_PEEK_OFF, &id, sizeof(id));
 
   // Success; no control messages.
   if (msg.msg_controllen == 0)
     return result;
 
   DCHECK(!(msg.msg_flags & MSG_CTRUNC));
@@ skipping 10 matching lines @@
         DCHECK(platform_handles->back().is_valid());
       }
     }
   }
 
   return result;
 }
 
 }  // namespace edk
 }  // namespace mojo