make base::SharedMemoryHandle a class on POSIX.

base/memory/shared_memory_android.cc

 // Copyright (c) 2011 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 "base/memory/shared_memory.h"
 
 #include <stddef.h>
 #include <sys/mman.h>
 
 #include "base/logging.h"
 #include "third_party/ashmem/ashmem.h"
 
 namespace base {
 
 // For Android, we use ashmem to implement SharedMemory. ashmem_create_region
 // will automatically pin the region. We never explicitly call pin/unpin. When
 // all the file descriptors from different processes associated with the region
 // are closed, the memory buffer will go away.
 
 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
-  DCHECK_EQ(-1, mapped_file_ );
+  DCHECK(!shm_.IsValid());
 
   if (options.size > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
   // "name" is just a label in ashmem. It is visible in /proc/pid/maps.
-  mapped_file_ = ashmem_create_region(
+  int fd = ashmem_create_region(
       options.name_deprecated == NULL ? "" : options.name_deprecated->c_str(),
       options.size);
-  if (-1 == mapped_file_) {
+  shm_ = SharedMemoryHandle::ImportHandle(fd);
+  if (!shm_.IsValid()) {
     DLOG(ERROR) << "Shared memory creation failed";
     return false;
   }
 
-  int err = ashmem_set_prot_region(mapped_file_,
+  int err = ashmem_set_prot_region(shm_.GetHandle(),
                                    PROT_READ | PROT_WRITE | PROT_EXEC);
   if (err < 0) {
     DLOG(ERROR) << "Error " << err << " when setting protection of ashmem";
     return false;
   }
 
   // Android doesn't appear to have a way to drop write access on an ashmem
   // segment for a single descriptor.  http://crbug.com/320865
-  readonly_mapped_file_ = dup(mapped_file_);
+  readonly_mapped_file_ = dup(shm_.GetHandle());
   if (-1 == readonly_mapped_file_) {
     DPLOG(ERROR) << "dup() failed";
     return false;
   }
 
   requested_size_ = options.size;
 
   return true;
 }
 
 bool SharedMemory::Delete(const std::string& name) {
   // Like on Windows, this is intentionally returning true as ashmem will
   // automatically releases the resource when all FDs on it are closed.
   return true;
 }
 
 bool SharedMemory::Open(const std::string& name, bool read_only) {
   // ashmem doesn't support name mapping
   NOTIMPLEMENTED();
   return false;
 }
 
 }  // namespace base