Factor out common error-code conversion code for PlatformFileErrorToNetError.

net/base/net_errors.cc

Index: net/base/net_errors.cc
diff --git a/net/base/net_errors.cc b/net/base/net_errors.cc
index 623c0716bbdfcd489e757c320cd930cfbea80d5f..b3b833054395ec07cdad299957ce2e7a130575ea 100644
--- a/net/base/net_errors.cc
+++ b/net/base/net_errors.cc
@@ -44,4 +44,18 @@ std::vector<int> GetAllErrorCodesForUma() {
       kAllErrorCodes, arraysize(kAllErrorCodes));
 }
 
+int PlatformFileErrorToNetError(
+    base::PlatformFileError file_error) {
+  switch (file_error) {
+    case base::PLATFORM_FILE_OK:
+      return net::OK;
+    case base::PLATFORM_FILE_ERROR_NOT_FOUND:
+      return net::ERR_FILE_NOT_FOUND;
+    case base::PLATFORM_FILE_ERROR_ACCESS_DENIED:
+      return net::ERR_ACCESS_DENIED;
+    default:
+      return net::ERR_FAILED;
+  }
+}
+
 }  // namespace net