Implement ScopedFD in terms of ScopedGeneric.

base/memory/discardable_memory_allocator_android.cc

 // Copyright 2013 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/discardable_memory_allocator_android.h"
 
 #include <sys/mman.h>
 #include <unistd.h>
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/containers/hash_tables.h"
 #include "base/file_util.h"
+#include "base/files/scoped_file.h"
 #include "base/logging.h"
 #include "base/memory/discardable_memory.h"
 #include "base/memory/scoped_vector.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "third_party/ashmem/ashmem.h"
 
 // The allocator consists of three parts (classes):
 // - DiscardableMemoryAllocator: entry point of all allocations (through its
 // Allocate() method) that are dispatched to the AshmemRegion instances (which
@@ skipping 29 matching lines @@
   if (size > std::numeric_limits<size_t>::max() - kPageSize + 1)
     return 0;
   const size_t mask = ~(kPageSize - 1);
   return (size + kPageSize - 1) & mask;
 }
 
 bool CreateAshmemRegion(const char* name,
                         size_t size,
                         int* out_fd,
                         void** out_address) {
-  int fd = ashmem_create_region(name, size);
-  if (fd < 0) {
+  base::ScopedFD fd(ashmem_create_region(name, size));
+  if (!fd) {

[viettrungluu, 2014/03/08 03:06:04]

So, it occurs to me that this is extremely confusing.

I think it'd be better for ScopedNullableGeneric to have is_valid/is_invalid
methods. (Though that throws into question the name "Nullable". D'oh.)

     DLOG(ERROR) << "ashmem_create_region() failed";
     return false;
   }
-  file_util::ScopedFD fd_closer(&fd);
 
-  const int err = ashmem_set_prot_region(fd, PROT_READ | PROT_WRITE);
+  const int err = ashmem_set_prot_region(fd.get(), PROT_READ | PROT_WRITE);
   if (err < 0) {
     DLOG(ERROR) << "Error " << err << " when setting protection of ashmem";
     return false;
   }
 
   // There is a problem using MAP_PRIVATE here. As we are constantly calling
   // Lock() and Unlock(), data could get lost if they are not written to the
   // underlying file when Unlock() gets called.
   void* const address = mmap(
       NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
@@ skipping 465 matching lines @@
   DCHECK_LE(ashmem_regions_.size(), 5U);
   const ScopedVector<AshmemRegion>::iterator it = std::find(
       ashmem_regions_.begin(), ashmem_regions_.end(), region);
   DCHECK_NE(ashmem_regions_.end(), it);
   std::swap(*it, ashmem_regions_.back());
   ashmem_regions_.pop_back();
 }
 
 }  // namespace internal
 }  // namespace base