Make it so net/ can be built without file:// support.

net/BUILD.gn

Index: net/BUILD.gn
===================================================================
--- net/BUILD.gn	(revision 268640)
+++ net/BUILD.gn	(working copy)
@@ -37,6 +37,11 @@
 use_v8_in_net = false  # TODO(brettw)!is_ios
 enable_built_in_dns = !is_ios
 
+declare_args() {
+  # Disables support for file URLs.  File URL support requires use of icu.
+  disable_file_support = false
+}
+
 enable_ftp_support = !is_ios
 
 config("net_config") {
@@ -44,6 +49,9 @@
   if (posix_avoid_mmap) {
     defines += [ "POSIX_AVOID_MMAP" ]
   }
+  if (disable_file_support) {
+    defines += [ "DISABLE_FILE_SUPPORT" ]
+  }
 }
 
 # Disables Windows warning about size to int truncations.
@@ -108,6 +116,19 @@
     }
   }
 
+  if (disable_file_support) {
+    sources -= [
+      "base/directory_lister.cc",
+      "base/directory_lister.h",
+      "url_request/url_request_file_dir_job.cc",
+      "url_request/url_request_file_dir_job.h",
+      "url_request/url_request_file_job.cc",
+      "url_request/url_request_file_job.h",
+      "url_request/file_protocol_handler.cc",
+      "url_request/file_protocol_handler.h",
+    ]
+  }
+
   if (!enable_ftp_support) {
     sources -= [
       "ftp/ftp_auth_cache.cc",