Refactor oemcrypto mock into stand alone reference code

Merge from Widevine repo of http://go/wvgerrit/46204
Refactor utility code - split the mock, step 1

Merge from Widevine repo of http://go/wvgerrit/46205
Move some OEMCrypto types to common header - split the mock, step 2

Merge from Widevine repo of http://go/wvgerrit/46206
Split mock into two -- step 3

Merge from Widevine repo of http://go/wvgerrit/47460
Split the mock into two -- step 3.5

The CL moves several files used by oemcrypto and cdm into a common
subdirectory, so that it may more easily be shared with partners.

The CORE_DISALLOW_COPY_AND_ASSIGN macro was moved to its own header in
the util/include directory.

This CL removes some references to the mock from other code, and puts
some constants and types, such as the definition of the keybox, into a
header in oemcrypto.

Test: tested as part of http://go/ag/4674759
bug: 76393338
Change-Id: I75b4bde7062ed8ee572c97ebc2f4da018f4be0c9

libwvdrmengine/cdm/util/include/clock.h

@@ -0,0 +1,24 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Clock - Platform independent interface for a time library
+//
+#ifndef WVCDM_UTIL_CLOCK_H_
+#define WVCDM_UTIL_CLOCK_H_
+
+#include <stdint.h>
+
+namespace wvcdm {
+
+// Provides time related information. The implementation is platform dependent.
+class Clock {
+ public:
+  Clock() {}
+  virtual ~Clock() {}
+
+  // Provides the number of seconds since an epoch - 01/01/1970 00:00 UTC
+  virtual int64_t GetCurrentTime();
+};
+
+}  // namespace wvcdm
+
+#endif  // WVCDM_UTIL_CLOCK_H_