Replace UniquePtr with std::unique_ptr

(This is a merge of http://go/wvgerrit/65264)

Now that we have C++11, we can remove Android's hand-rolled UniquePtr in
favor of std::unique_ptr.

Bug: 111851141
Test: Android Unit Tests
Change-Id: I96c2015aa2422da66a4bcbefb927dacc5f6e782f

libwvdrmengine/cdm/include/wv_content_decryption_module.h

@@ -6,8 +6,8 @@
 #define CDM_BASE_WV_CONTENT_DECRYPTION_MODULE_H_
 
 #include <map>
+#include <memory>
 
-#include <UniquePtr.h>
 #include <utils/RefBase.h>
 
 #include "cdm_identifier.h"
@@ -144,7 +144,7 @@ class WvContentDecryptionModule : public android::RefBase, public TimerHandler {
     CdmInfo();
 
     FileSystem file_system;
-    UniquePtr<CdmEngine> cdm_engine;
+    std::unique_ptr<CdmEngine> cdm_engine;
   };
 
   // Finds the CdmEngine instance for the given identifier, creating one if