Add Max-Res Decode Engine to CDM Core

(This is a port of http://go/wvgerrit/11555 from the Widevine CDM
repo.)

Bug: 16034599
Change-Id: Ie69afac7d89e27623adbc84d2baebccf1d1ba6e6

libwvdrmengine/cdm/core/test/license_unittest.cpp

@@ -51,6 +51,9 @@ const std::string kWebmMimeType = "video/webm";
 namespace wvcdm {
 
 class LicenseTest : public ::testing::Test {
+ public:
+  LicenseTest() : policy_engine_(NULL) {}
+
  protected:
   virtual void SetUp() {
     session_ = new CryptoSession();