1) Change return type to WvCasStatus for functions in wv_cas_types.cc.

2) Add a binary wv_cas_types_example.
3) Surface wv_cas_key_fetcher *source code* to partner to serve as an example of how they would make a HTTP request to acquire an entitlement key from license server.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=229953562

example/wv_cas_ecm_example.cc

@@ -8,12 +8,23 @@
 
 // Example of how to use the wv_cas_ecm library.
 
+#include <cassert>
+#include <fstream>
 #include <iostream>
 #include <string>
 
+#include "gflags/gflags.h"
 #include "media_cas_packager_sdk/public/wv_cas_ecm.h"
 #include "media_cas_packager_sdk/public/wv_cas_types.h"
 
+DEFINE_int32(content_iv_size, 8, "Content IV size");
+DEFINE_bool(key_rotation, true, "Whether key rotation is enabled");
+DEFINE_string(crypto_mode, "CSA2", "Only CBC, CTR, or CSA2 is allowed");
+DEFINE_int32(ecm_pid, 149, "PID for the ECM packet");
+DEFINE_string(output_file, "",
+              "If specified, generated ECM TS packet will be written to the "
+              "specified output file path");
+
 const char kCsaEvenKey[] = "even_key";                    // 8 bytes
 const char kEvenContentIv8Bytes[] = "even_iv.";           // 8 bytes
 const char kEvenEntitlementKeyId[] = "fake_key_id1....";  // 16 bytes
@@ -24,26 +35,45 @@ const char kOddContentIv8Bytes[] = "odd_iv..";           // 8 bytes
 const char kOddEntitlementKeyId[] = "fake_key_id2....";  // 16 bytes
 const char kOddEntitlementKey[] =
     "fakefakefakefakefakefakefake2...";  // 32 bytes
+const size_t kTsPacketSize = 188;
+
+widevine::cas::CryptoMode GetCryptoMode() {
+  if (FLAGS_crypto_mode.compare("CBC") == 0) {
+    return widevine::cas::CryptoMode::kAesCbc;
+  }
+  if (FLAGS_crypto_mode.compare("CTR") == 0) {
+    return widevine::cas::CryptoMode::kAesCtr;
+  }
+  return widevine::cas::CryptoMode::kDvbCsa2;
+}
 
 int main(int argc, char **argv) {
+  gflags::ParseCommandLineFlags(&argc, &argv, true);
+  // Generate ECM.
   widevine::cas::WvCasEcm wv_cas_ecm;
   widevine::cas::WvCasStatus status = wv_cas_ecm.Initialize(
-      /* content_iv_size= */ 8, /* key_rotation_enabled= */ true,
-      widevine::cas::CryptoMode::kDvbCsa2);
+      FLAGS_content_iv_size, FLAGS_key_rotation, GetCryptoMode());
   if (status != widevine::cas::OK) {
     std::cerr << "Failed to initialize WV CAS ECM, error: "
               << widevine::cas::GetWvCasStatusMessage(status)
               << std::endl;
   }
   std::string ecm;
-  status = wv_cas_ecm.GenerateEcm(
-      kCsaEvenKey, kEvenContentIv8Bytes, kEvenEntitlementKeyId,
-      kEvenEntitlementKey, kCsaOddKey, kOddContentIv8Bytes,
-      kOddEntitlementKeyId, kOddEntitlementKey, &ecm);
+  if (FLAGS_key_rotation) {
+    status = wv_cas_ecm.GenerateEcm(
+        kCsaEvenKey, kEvenContentIv8Bytes, kEvenEntitlementKeyId,
+        kEvenEntitlementKey, kCsaOddKey, kOddContentIv8Bytes,
+        kOddEntitlementKeyId, kOddEntitlementKey, &ecm);
+  } else {
+    status = wv_cas_ecm.GenerateSingleKeyEcm(kCsaEvenKey, kEvenContentIv8Bytes,
+                                             kEvenEntitlementKeyId,
+                                             kEvenEntitlementKey, &ecm);
+  }
   if (status != widevine::cas::OK) {
     std::cerr << "Failed to generate WV CAS ECM, error: "
               << widevine::cas::GetWvCasStatusMessage(status)
               << std::endl;
+    return -1;
   } else {
     std::cout << "ECM size: " << ecm.size() << std::endl;
     std::cout << "ECM bytes: ";
@@ -52,6 +82,30 @@ int main(int argc, char **argv) {
     }
     std::cout << std::endl;
   }
+  // Generate ECM TS Packet.
+  uint8_t packet[kTsPacketSize];
+  uint8_t continuity_counter;  // not used.
+  status = wv_cas_ecm.GenerateTsPacket(ecm, FLAGS_ecm_pid,
+                                       /* table_id= */ 0x80,
+                                       &continuity_counter, packet);
+  if (status != widevine::cas::OK) {
+    std::cerr << "Failed to create ECM TS packet" << std::endl;
+    return -1;
+  } else {
+    std::cout << "TS packet bytes: ";
+    for (size_t i = 0; i < kTsPacketSize; i++) {
+      printf("'\\x%02x', ", static_cast<uint16_t>(packet[i]));
+    }
+    std::cout << std::endl;
+  }
+  // Write ECM TS Packet to a file.
+  if (!FLAGS_output_file.empty()) {
+    std::ofstream file;
+    file.open(FLAGS_output_file.c_str(), std::ios_base::binary);
+    assert(file.is_open());
+    file.write(reinterpret_cast<char *>(packet), kTsPacketSize);
+    file.close();
+  }
 
   return 0;
 }