Reland of Mojo: Eliminate duplicate C API symbols

mojo/edk/embedder/embedder.cc

Index: mojo/edk/embedder/embedder.cc
diff --git a/mojo/edk/embedder/embedder.cc b/mojo/edk/embedder/embedder.cc
index 6320365ec11a0a8b2a6334087d5b4ce366291ae2..66cc96f82e2e76b6199897f802ec029cd6ef0059 100644
--- a/mojo/edk/embedder/embedder.cc
+++ b/mojo/edk/embedder/embedder.cc
@@ -15,6 +15,7 @@
 #include "base/task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "mojo/edk/embedder/embedder_internal.h"
+#include "mojo/edk/embedder/entrypoints.h"
 #include "mojo/edk/embedder/platform_channel_pair.h"
 #include "mojo/edk/embedder/process_delegate.h"
 #include "mojo/edk/system/core.h"
@@ -68,6 +69,10 @@
 }
 
 void Init() {
+  MojoSystemThunks thunks = MakeSystemThunks();
+  size_t expected_size = MojoEmbedderSetSystemThunks(&thunks);
+  DCHECK_EQ(expected_size, sizeof(thunks));
+
   internal::g_core = new Core();
 }