Support Windows FILE_FLAG_SEQUENTIAL_SCAN in base::File.

FILE_FLAG_SEQUENTIAL_SCAN is a hint to the system that a file will be
read sequentially from beginning to end.

It is required to pre-read modules efficiently.

BUG=547794

Review URL: https://codereview.chromium.org/1424943006

Cr-Commit-Position: refs/heads/master@{#357151}

base/files/file.h

@@ -85,6 +85,7 @@ class BASE_EXPORT File {
     FLAG_TERMINAL_DEVICE = 1 << 16,   // Serial port flags.
     FLAG_BACKUP_SEMANTICS = 1 << 17,  // Used on Windows only.
     FLAG_EXECUTE = 1 << 18,           // Used on Windows only.
+    FLAG_SEQUENTIAL_SCAN = 1 << 19,   // Used on Windows only.
   };
 
   // This enum has been recorded in multiple histograms. If the order of the

base/files/file_win.cc

@@ -375,6 +375,8 @@ void File::DoInitialize(const FilePath& path, uint32 flags) {
     create_flags |= FILE_FLAG_DELETE_ON_CLOSE;
   if (flags & FLAG_BACKUP_SEMANTICS)
     create_flags |= FILE_FLAG_BACKUP_SEMANTICS;
+  if (flags & FLAG_SEQUENTIAL_SCAN)
+    create_flags |= FILE_FLAG_SEQUENTIAL_SCAN;
 
   file_.Set(CreateFile(path.value().c_str(), access, sharing, NULL,
                        disposition, create_flags, NULL));