Convert remaining scoped_ptr -> std::unique_ptr in //mojo/edk (minus js).

mojo/python/system/mojo_embedder.pyx

Index: mojo/python/system/mojo_embedder.pyx
diff --git a/mojo/python/system/mojo_embedder.pyx b/mojo/python/system/mojo_embedder.pyx
index 75ae38797f46c2c75df79816d408bd28b1ea271c..bd30ddd77f45957845eb0b75ee8bd8f3b45960b4 100644
--- a/mojo/python/system/mojo_embedder.pyx
+++ b/mojo/python/system/mojo_embedder.pyx
@@ -13,9 +13,12 @@ import mojo_system_impl
 cdef extern from "third_party/cython/python_export.h":
   pass
 
-cdef extern from "base/memory/scoped_ptr.h":
-  cdef cppclass scoped_ptr[T]:
-    scoped_ptr(T*)
+# TODO(vtl): More recent versions of cython have a libcpp.memory with
+# |unique_ptr|.
+cdef extern from "<memory>" \
+    namespace "std" nogil:
+  cdef cppclass unique_ptr[T]:
+    unique_ptr(T*)
 
 cdef extern from "mojo/edk/embedder/platform_support.h" \
     namespace "mojo::embedder" nogil:
@@ -29,7 +32,7 @@ cdef extern from "mojo/edk/embedder/simple_platform_support.h" \
 
 cdef extern from "mojo/edk/embedder/embedder.h" nogil:
   cdef void InitCEmbedder "mojo::embedder::Init"(
-      scoped_ptr[PlatformSupport] platform_support)
+      unique_ptr[PlatformSupport] platform_support)
 
 cdef extern from "mojo/public/platform/native/system_thunks.h" nogil:
   cdef struct MojoSystemThunks:
@@ -40,8 +43,7 @@ cdef extern from "mojo/edk/embedder/test_embedder.h" nogil:
   cdef bool ShutdownCEmbedderForTest "mojo::embedder::test::Shutdown"()
 
 def Init():
-  InitCEmbedder(scoped_ptr[PlatformSupport](
-      new SimplePlatformSupport()))
+  InitCEmbedder(unique_ptr[PlatformSupport](new SimplePlatformSupport()))
   cdef MojoSystemThunks thunks = MojoMakeSystemThunks()
   mojo_system.SetSystemThunks(<uintptr_t>(&thunks))
   mojo_system_impl.SetSystemThunks(<uintptr_t>(&thunks))