Do not depend on wvcdm::Clock in OEC tests

Merge from widevine repo of http://go/wvgerrit/14669

This fixes two timing-related test failures when running the OEMCrypto
tests in the CE test suite.  The failures were caused by the TestHost
Clock implementation, which is a fake.  Since there is no clear reason
for OEMCrypto/mock to rely on wvcdm::Clock, this replaces it with
time(NULL).  Incidentally, this also makes the time source consistent
with the tests themselves, which were already using time(NULL).

Change-Id: I0fad51f14d45f99526146da05b757d4ba7b6aba0

libwvdrmengine/oemcrypto/mock/src/oemcrypto_usage_table_mock.cpp

@@ -5,6 +5,8 @@
 #include "oemcrypto_usage_table_mock.h"
 
 #include <string.h>
+#include <time.h>
+
 #include <string>
 #include <vector>
 
@@ -13,7 +15,6 @@
 #include <openssl/rand.h>
 #include <openssl/sha.h>
 
-#include "clock.h"
 #include "file_store.h"
 #include "log.h"
 #include "oemcrypto_engine_mock.h"
@@ -24,12 +25,10 @@
 
 namespace wvoec_mock {
 
-wvcdm::Clock UsageTableEntry::clock_;
-
 UsageTableEntry::UsageTableEntry(const std::vector<uint8_t> &pst_hash,
                                  SessionContext *ctx)
     : pst_hash_(pst_hash),
-      time_of_license_received_(clock_.GetCurrentTime()),
+      time_of_license_received_(time(NULL)),
       time_of_first_decrypt_(0),
       time_of_last_decrypt_(0),
       status_(kUnused),
@@ -75,7 +74,7 @@ void UsageTableEntry::Deactivate() {
 }
 
 bool UsageTableEntry::UpdateTime() {
-  int64_t now = clock_.GetCurrentTime();
+  int64_t now = time(NULL);
   switch (status_) {
     case kUnused:
       status_ = kActive;
@@ -104,7 +103,7 @@ OEMCryptoResult UsageTableEntry::ReportUsage(SessionContext *session,
     LOGE("ReportUsage: buffer was null pointer.");
     return OEMCrypto_ERROR_INVALID_CONTEXT;
   }
-  int64_t now = clock_.GetCurrentTime();
+  int64_t now = time(NULL);
   buffer->seconds_since_license_received =
       wvcdm::htonll64(now - time_of_license_received_);
   buffer->seconds_since_first_decrypt =

libwvdrmengine/oemcrypto/mock/src/oemcrypto_usage_table_mock.h

@@ -10,7 +10,6 @@
 #include <string>
 #include <vector>
 
-#include "clock.h"
 #include "lock.h"
 #include "OEMCryptoCENC.h"
 #include "openssl/sha.h"
@@ -73,7 +72,6 @@ class UsageTableEntry {
   std::vector<uint8_t> mac_key_client_;
 
   SessionContext *session_;
-  static wvcdm::Clock clock_;
 };
 
 class UsageTable {