Add LINKER_INITIALIZER marker to MemoryMappedFile::Region::kWholeFile

base/files/memory_mapped_file.h

Index: base/files/memory_mapped_file.h
diff --git a/base/files/memory_mapped_file.h b/base/files/memory_mapped_file.h
index dc5680615daf4fb10762ae663f358d0f0f2c7a98..8a7f045f351a0365d496f37f5824607cacfdc12e 100644
--- a/base/files/memory_mapped_file.h
+++ b/base/files/memory_mapped_file.h
@@ -41,7 +41,7 @@ class BASE_EXPORT MemoryMappedFile {
    private:
     // This ctor is used only by kWholeFile, to construct a zero-sized Region
     // (which is forbidden by the public ctor) and uniquely identify kWholeFile.
-    Region();
+    Region(base::LinkerInitialized);
   };
 
   // Opens an existing file and maps it into memory. Access is restricted to