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

mojo/dart/dart_snapshotter/main.cc

Index: mojo/dart/dart_snapshotter/main.cc
diff --git a/mojo/dart/dart_snapshotter/main.cc b/mojo/dart/dart_snapshotter/main.cc
index 48e5341af148b4f103082493ff074bdd9a7e6dda..7fb52567fb66ca9d6035210626937a2ca7fa2a7a 100644
--- a/mojo/dart/dart_snapshotter/main.cc
+++ b/mojo/dart/dart_snapshotter/main.cc
@@ -61,8 +61,9 @@ int main(int argc, const char* argv[]) {
   }
 
   // Initialize mojo.
-  mojo::embedder::Init(
-      make_scoped_ptr(new mojo::embedder::SimplePlatformSupport()));
+  // TODO(vtl): Use make_unique when C++14 is available.
+  mojo::embedder::Init(std::unique_ptr<mojo::embedder::PlatformSupport>(
+      new mojo::embedder::SimplePlatformSupport()));
 
   InitDartVM();