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

content/browser/browser_child_process_host_impl.cc

Index: content/browser/browser_child_process_host_impl.cc
diff --git a/content/browser/browser_child_process_host_impl.cc b/content/browser/browser_child_process_host_impl.cc
index f15b4fc1aebbba1bd904730ad2f7ca2d03535737..eb181d5cd5ccd57e186bd59e9fbd686a7b6008e9 100644
--- a/content/browser/browser_child_process_host_impl.cc
+++ b/content/browser/browser_child_process_host_impl.cc
@@ -164,6 +164,7 @@ void BrowserChildProcessHostImpl::Launch(
     switches::kTraceToConsole,
     switches::kV,
     switches::kVModule,
+    "use-new-edk",  // TODO(use_chrome_edk): temporary.
   };
   cmd_line->CopySwitchesFrom(browser_command_line, kForwardSwitches,
                              arraysize(kForwardSwitches));