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

mojo/edk/embedder/platform_support.h

Index: mojo/edk/embedder/platform_support.h
diff --git a/third_party/mojo/src/mojo/edk/embedder/platform_support.h b/mojo/edk/embedder/platform_support.h
similarity index 96%
copy from third_party/mojo/src/mojo/edk/embedder/platform_support.h
copy to mojo/edk/embedder/platform_support.h
index 02186161082252032a601d863a074d0f1294bae1..160ba79b320425d124aea338e684a9470ea73568 100644
--- a/third_party/mojo/src/mojo/edk/embedder/platform_support.h
+++ b/mojo/edk/embedder/platform_support.h
@@ -12,7 +12,7 @@
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
-namespace embedder {
+namespace edk {
 
 class PlatformSharedBuffer;
 
@@ -37,7 +37,7 @@ class MOJO_SYSTEM_IMPL_EXPORT PlatformSupport {
   MOJO_DISALLOW_COPY_AND_ASSIGN(PlatformSupport);
 };
 
-}  // namespace embedder
+}  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_EMBEDDER_PLATFORM_SUPPORT_H_