Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

mojo/fetcher/BUILD.gn

Index: mojo/fetcher/BUILD.gn
diff --git a/mojo/fetcher/BUILD.gn b/mojo/fetcher/BUILD.gn
index da681cacba2cfe02b86fd7eb43b98e00cbdac41e..c37f3f7796f5820687246b05344e32c1ea1d9f7c 100644
--- a/mojo/fetcher/BUILD.gn
+++ b/mojo/fetcher/BUILD.gn
@@ -39,7 +39,12 @@ source_set("fetcher") {
     "//mojo/shell",
     "//mojo/util:filename_util",
     "//net",
-    "//third_party/mojo/src/mojo/edk/system",
     "//url",
   ]
+
+  if (use_chrome_edk) {
+    deps += [ "//mojo/edk/system" ]
+  } else {
+    deps += [ "//third_party/mojo/src/mojo/edk/system" ]
+  }
 }