Improve process launch handle sharing API.

content/public/browser/BUILD.gn

Index: content/public/browser/BUILD.gn
diff --git a/content/public/browser/BUILD.gn b/content/public/browser/BUILD.gn
index ee2c9c8cbfb14a53471aaa06a6e466804dd88ba1..45fc5513f10da3e90f43f81dbba9ace27820450e 100644
--- a/content/public/browser/BUILD.gn
+++ b/content/public/browser/BUILD.gn
@@ -114,7 +114,6 @@ source_set("browser_sources") {
     "download_url_parameters.h",
     "favicon_status.cc",
     "favicon_status.h",
-    "file_descriptor_info.h",
     "focused_node_details.h",
     "font_list_async.h",
     "global_request_id.h",
@@ -339,6 +338,10 @@ source_set("browser_sources") {
     "//content/browser",
   ]
 
+  if (is_posix) {
+    sources += [ "posix_file_descriptor_info.h" ]
+  }
+
   if (is_android) {
     deps += [ "//ui/android" ]
   }