Sandboxed processes must ask the browser to allocate shared memory.

content/child/child_thread_impl.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 "content/child/child_thread_impl.h"
 
 #include <signal.h>
 #include <string>
 #include <utility>
 
@@ skipping 551 matching lines @@
     size_t buf_size) {
   DCHECK(base::MessageLoop::current() == message_loop());
   return AllocateSharedMemory(buf_size, this);
 }
 
 // static
 scoped_ptr<base::SharedMemory> ChildThreadImpl::AllocateSharedMemory(
     size_t buf_size,
     IPC::Sender* sender) {
   scoped_ptr<base::SharedMemory> shared_buf;
-#if defined(OS_WIN)
-  shared_buf.reset(new base::SharedMemory);
-  if (!shared_buf->CreateAnonymous(buf_size)) {
-    NOTREACHED();
-    return nullptr;
-  }
-#else
-  // On POSIX, we need to ask the browser to create the shared memory for us,
-  // since this is blocked by the sandbox.
+  // Ask the browser to create the shared memory, since this is blocked by the
+  // sandbox on most platforms.
   base::SharedMemoryHandle shared_mem_handle;
   if (sender->Send(new ChildProcessHostMsg_SyncAllocateSharedMemory(
-                           buf_size, &shared_mem_handle))) {
+          buf_size, &shared_mem_handle))) {
     if (base::SharedMemory::IsHandleValid(shared_mem_handle)) {
       shared_buf.reset(new base::SharedMemory(shared_mem_handle, false));
     } else {
       NOTREACHED() << "Browser failed to allocate shared memory";
       return nullptr;
     }
   } else {
     // Send is allowed to fail during shutdown. Return null in this case.
     return nullptr;
   }
-#endif
   return shared_buf;
 }
 
 bool ChildThreadImpl::OnMessageReceived(const IPC::Message& msg) {
   if (mojo_application_->OnMessageReceived(msg))
     return true;
 
   // Resource responses are sent to the resource dispatcher.
   if (resource_dispatcher_->OnMessageReceived(msg))
     return true;
@@ skipping 126 matching lines @@
 void ChildThreadImpl::EnsureConnected() {
   VLOG(0) << "ChildThreadImpl::EnsureConnected()";
   base::Process::Current().Terminate(0, false);
 }
 
 bool ChildThreadImpl::IsInBrowserProcess() const {
   return browser_process_io_runner_;
 }
 
 }  // namespace content