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

mojo/edk/system/async_waiter.h

Index: mojo/edk/system/async_waiter.h
diff --git a/third_party/mojo/src/mojo/edk/system/async_waiter.h b/mojo/edk/system/async_waiter.h
similarity index 96%
copy from third_party/mojo/src/mojo/edk/system/async_waiter.h
copy to mojo/edk/system/async_waiter.h
index 2c4d770154602082910fc9c3733bae9b831c1883..19ef5d6fee43cc2fa08d186f6da53c330b5f89f7 100644
--- a/third_party/mojo/src/mojo/edk/system/async_waiter.h
+++ b/mojo/edk/system/async_waiter.h
@@ -12,7 +12,7 @@
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
-namespace system {
+namespace edk {
 
 // An |Awakable| implementation that just calls a given callback object.
 class MOJO_SYSTEM_IMPL_EXPORT AsyncWaiter final : public Awakable {
@@ -32,7 +32,7 @@ class MOJO_SYSTEM_IMPL_EXPORT AsyncWaiter final : public Awakable {
   MOJO_DISALLOW_COPY_AND_ASSIGN(AsyncWaiter);
 };
 
-}  // namespace system
+}  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_ASYNC_WAITER_H_