Add a PartialPreReadImage function to file_util (on Windows).

base/file_util.h

Index: base/file_util.h
diff --git a/base/file_util.h b/base/file_util.h
index 53264c12c5709c67e46490bffb87f5f982c8af65..1720e602fc15159f8da2d059e8b6e37fd8cc2a14 100644
--- a/base/file_util.h
+++ b/base/file_util.h
@@ -615,16 +615,6 @@ BASE_EXPORT bool HasFileBeenModifiedSince(
     const FileEnumerator::FindInfo& find_info,
     const base::Time& cutoff_time);
 
-#if defined(OS_WIN)
-  // Loads the file passed in as an image section and touches pages to avoid
-  // subsequent hard page faults during LoadLibrary. The size to be pre read
-  // is passed in. If it is 0 then the whole file is paged in. The step size
-  // which indicates the number of bytes to skip after every page touched is
-  // also passed in.
-bool BASE_EXPORT PreReadImage(const wchar_t* file_path, size_t size_to_read,
-                              size_t step_size);
-#endif  // OS_WIN
-
 #if defined(OS_LINUX)
 // Broad categories of file systems as returned by statfs() on Linux.
 enum FileSystemType {