[mojo-edk] Expose portable API for platform handle wrapping

mojo/edk/embedder/platform_shared_buffer.h

Index: mojo/edk/embedder/platform_shared_buffer.h
diff --git a/mojo/edk/embedder/platform_shared_buffer.h b/mojo/edk/embedder/platform_shared_buffer.h
index 45be7233c4f74c5d7e261ad4e058ef5b80b473da..8f0c420430b5b7531ed16fd17eff96708857142a 100644
--- a/mojo/edk/embedder/platform_shared_buffer.h
+++ b/mojo/edk/embedder/platform_shared_buffer.h
@@ -16,6 +16,7 @@
 #include "base/synchronization/lock.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/system_impl_export.h"
+#include "mojo/public/c/system/types.h"
 
 namespace mojo {
 namespace edk {
@@ -61,6 +62,17 @@ class MOJO_SYSTEM_IMPL_EXPORT PlatformSharedBuffer
       bool read_only,
       base::SharedMemoryHandle handle);
 
+  // Returns a base::SharedMemoryHandle given a PlatformHandle and some
+  // associated settings.
+  static base::SharedMemoryHandle GetSharedMemoryHandleFromPlatformHandle(
+      MojoPlatformHandle platform_handle,
+      size_t size,
+      bool read_only);
+
+  // Returns a PlatformHandle from a given base::SharedMemoryHandle.
+  static PlatformHandle GetPlatformHandleFromSharedMemoryHandle(
+      base::SharedMemoryHandle memory_handle);
+
   // Gets the size of shared buffer (in number of bytes).
   size_t GetNumBytes() const;