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_cert.cpp

@@ -15,7 +15,7 @@ namespace wvoec_ref {
 
 class CertOnlyCryptoEngine : public CryptoEngine {
  public:
-  explicit CertOnlyCryptoEngine(scoped_ptr<wvcdm::FileSystem> file_system)
+  explicit CertOnlyCryptoEngine(std::unique_ptr<wvcdm::FileSystem> file_system)
       : CryptoEngine(file_system) {}
 
   bool config_local_display_only() { return true; }
@@ -30,7 +30,7 @@ class CertOnlyCryptoEngine : public CryptoEngine {
 };
 
 CryptoEngine* CryptoEngine::MakeCryptoEngine(
-    scoped_ptr<wvcdm::FileSystem> file_system) {
+    std::unique_ptr<wvcdm::FileSystem> file_system) {
   return new CertOnlyCryptoEngine(file_system);
 }