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

ipc/mojo/async_handle_waiter.cc

Index: ipc/mojo/async_handle_waiter.cc
diff --git a/ipc/mojo/async_handle_waiter.cc b/ipc/mojo/async_handle_waiter.cc
index b9e68d7c4539886059b8428617eb43121eb19b4d..854c8e30d51db7dd3b67fbaeac51a9db63470e83 100644
--- a/ipc/mojo/async_handle_waiter.cc
+++ b/ipc/mojo/async_handle_waiter.cc
@@ -9,7 +9,12 @@
 #include "base/bind_helpers.h"
 #include "base/location.h"
 #include "base/logging.h"
+
+#if defined(USE_CHROME_EDK)
+#include "mojo/edk/embedder/embedder.h"
+#else
 #include "third_party/mojo/src/mojo/edk/embedder/embedder.h"
+#endif
 
 namespace IPC {
 namespace internal {
@@ -86,6 +91,11 @@ class AsyncHandleWaiter::Context
   }
 
   void DidProcessIOEvent() override {
+    // This object could have been constructed in another's class's
+    // DidProcessIOEvent.
+    if (io_loop_level_== 0)
+      return;
+
     DCHECK_GE(io_loop_level_, 1);
 
     // Leaving a nested loop.