Replace scoped_ptr With std::unique_ptr

(This is a merge of http://go/wvgerrit/65782)

We have had our own scoped_ptr implementation that is used throughout
the codebase. Now that we support C++11, we can replace these with
std::unique_ptr.

Doing this replacement exposed a few places where the two were not
interchangeable. OEMCrypto Ref was doing some unsafe things with passing
scoped_ptrs to functions and has been updated to use move semantics. And
a few constructors were explicitly constructing a scoped_ptr with NULL,
which is ambiguous with std::unique_ptr. These have been replaced with
default constructor calls.

Bug: 111851141
Test: CE CDM Unit Tests
Test: Android Unit Tests
Change-Id: I37d6d7aad4906709381c74f0c5439f826d2be768

libwvdrmengine/oemcrypto/ref/src/oemcrypto_engine_device_properties.cpp

@@ -7,11 +7,13 @@
 
 #include "oemcrypto_engine_ref.h"
 
+#include <utility>
+
 namespace wvoec_ref {
 
 CryptoEngine* CryptoEngine::MakeCryptoEngine(
-    scoped_ptr<wvcdm::FileSystem> file_system) {
-  return new CryptoEngine(file_system);
+    std::unique_ptr<wvcdm::FileSystem>&& file_system) {
+  return new CryptoEngine(std::move(file_system));
 }
 
 }  // namespace wvoec_ref