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/include/device_files.h

@@ -13,7 +13,6 @@
 
 #include "device_files.pb.h"
 #include "disallow_copy_and_assign.h"
-#include "scoped_ptr.h"
 #include "wv_cdm_types.h"
 
 #if defined(UNIT_TEST)