base: Move MemoryMappedFile out of file_util.h and into its own header file.

base/files/memory_mapped_file.cc

Index: base/files/memory_mapped_file.cc
diff --git a/base/files/memory_mapped_file.cc b/base/files/memory_mapped_file.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9e98bc6ff782eb2a10798d0fcef41d40f519ea5d
--- /dev/null
+++ b/base/files/memory_mapped_file.cc
@@ -0,0 +1,58 @@
+// 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/files/memory_mapped_file.h"
+
+#include "base/file_path.h"
+#include "base/logging.h"
+
+namespace base {
+
+MemoryMappedFile::~MemoryMappedFile() {
+  CloseHandles();
+}
+
+bool MemoryMappedFile::Initialize(const FilePath& file_name) {
+  if (IsValid())
+    return false;
+
+  if (!MapFileToMemory(file_name)) {
+    CloseHandles();
+    return false;
+  }
+
+  return true;
+}
+
+bool MemoryMappedFile::Initialize(PlatformFile file) {
+  if (IsValid())
+    return false;
+
+  file_ = file;
+
+  if (!MapFileToMemoryInternal()) {
+    CloseHandles();
+    return false;
+  }
+
+  return true;
+}
+
+bool MemoryMappedFile::IsValid() const {
+  return data_ != NULL;
+}
+
+bool MemoryMappedFile::MapFileToMemory(const FilePath& file_name) {
+  file_ = CreatePlatformFile(file_name, PLATFORM_FILE_OPEN | PLATFORM_FILE_READ,
+                             NULL, NULL);
+
+  if (file_ == kInvalidPlatformFileValue) {
+    DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
+    return false;
+  }
+
+  return MapFileToMemoryInternal();
+}
+
+}  // namespace base