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/cdm/core/src/crypto_session.cpp

@@ -2577,7 +2577,8 @@ void CryptoSession::IncrementIV(uint64_t increase_by,
 
 // The factory will either be set by WvCdmTestBase, or a default factory is
 // created on the first call to MakeCryptoSession.
-scoped_ptr<CryptoSessionFactory> CryptoSession::factory_(NULL);
+std::unique_ptr<CryptoSessionFactory> CryptoSession::factory_ =
+    std::unique_ptr<CryptoSessionFactory>();
 
 CryptoSession* CryptoSession::MakeCryptoSession(
     metrics::CryptoMetrics* crypto_metrics) {