Initial version of new file wrapper

webrtc/base/BUILD.gn

Index: webrtc/base/BUILD.gn
diff --git a/webrtc/base/BUILD.gn b/webrtc/base/BUILD.gn
index bcc6ad901e319a4245003df45d6be908cd9e3d21..ebfb92d4069f296f8b808fc3332531bdb279bed4 100644
--- a/webrtc/base/BUILD.gn
+++ b/webrtc/base/BUILD.gn
@@ -123,6 +123,8 @@ static_library("rtc_base_approved") {
     "event_tracer.h",
     "exp_filter.cc",
     "exp_filter.h",
+    "file.cc",
+    "file.h",
     "location.cc",
     "location.h",
     "md5.cc",
@@ -170,6 +172,14 @@ static_library("rtc_base_approved") {
     "trace_event.h",
   ]
 
+  if (is_posix) {
+    sources += [ "file_posix.cc" ]
+  }
+
+  if (is_win) {
+    sources += [ "file_win.cc" ]
+  }
+
   if (build_with_chromium) {
     # Dependency on chromium's logging (in //base).
     deps += [ "//base:base" ]